diff --git a/build.zig b/build.zig
index 6acf08a0e5..2dc9c671ec 100644
--- a/build.zig
+++ b/build.zig
@@ -20,8 +20,8 @@ pub fn build(b: *Builder) !void {
         b.allocator,
         [][]const u8{ b.cache_root, "langref.html" },
     ) catch unreachable;
-    var docgen_cmd = b.addCommand(null, b.env_map, [][]const u8{
-        docgen_exe.getOutputPath(),
+    var docgen_cmd = docgen_exe.run();
+    docgen_cmd.addArgs([][]const u8{
         rel_zig_exe,
         "doc" ++ os.path.sep_str ++ "langref.html.in",
         langref_out_path,
diff --git a/doc/langref.html.in b/doc/langref.html.in
index b816d65289..39d7e4449c 100644
--- a/doc/langref.html.in
+++ b/doc/langref.html.in
@@ -7914,8 +7914,7 @@ pub fn build(b: *Builder) void {
 
     b.default_step.dependOn(&exe.step);
 
-    const run_cmd = b.addCommand(".", b.env_map, [][]const u8{exe.getOutputPath()});
-    run_cmd.step.dependOn(&exe.step);
+    const run_cmd = exe.run();
 
     const test_step = b.step("test", "Test the program");
     test_step.dependOn(&run_cmd.step);
diff --git a/example/mix_o_files/build.zig b/example/mix_o_files/build.zig
index 623ec63de9..c945ce6bd6 100644
--- a/example/mix_o_files/build.zig
+++ b/example/mix_o_files/build.zig
@@ -4,14 +4,13 @@ pub fn build(b: *Builder) void {
     const obj = b.addObject("base64", "base64.zig");
 
     const exe = b.addExecutable("test", null);
-    exe.addCSourceFile("test.c",[][]const u8{"-std=c99"});
+    exe.addCSourceFile("test.c", [][]const u8{"-std=c99"});
     exe.addObject(obj);
     exe.linkSystemLibrary("c");
 
     b.default_step.dependOn(&exe.step);
 
-    const run_cmd = b.addCommand(".", b.env_map, [][]const u8{exe.getOutputPath()});
-    run_cmd.step.dependOn(&exe.step);
+    const run_cmd = exe.run();
 
     const test_step = b.step("test", "Test the program");
     test_step.dependOn(&run_cmd.step);
diff --git a/example/shared_library/build.zig b/example/shared_library/build.zig
index 5eaa4f4402..37af059ae0 100644
--- a/example/shared_library/build.zig
+++ b/example/shared_library/build.zig
@@ -10,8 +10,7 @@ pub fn build(b: *Builder) void {
 
     b.default_step.dependOn(&exe.step);
 
-    const run_cmd = b.addCommand(".", b.env_map, [][]const u8{exe.getOutputPath()});
-    run_cmd.step.dependOn(&exe.step);
+    const run_cmd = exe.run();
 
     const test_step = b.step("test", "Test the program");
     test_step.dependOn(&run_cmd.step);
diff --git a/src/all_types.hpp b/src/all_types.hpp
index c6826664ef..ec14382a2b 100644
--- a/src/all_types.hpp
+++ b/src/all_types.hpp
@@ -1087,7 +1087,6 @@ struct RootStruct {
     Buf *path; // relative to root_package->root_src_dir
     ZigList<size_t> *line_offsets;
     Buf *source_code;
-    AstNode *c_import_node;
     ZigLLVMDIFile *di_file;
 };
 
@@ -1746,13 +1745,12 @@ struct CodeGen {
 
     Buf triple_str;
     Buf global_asm;
-    Buf *out_h_path;
-    Buf *out_lib_path;
-    Buf artifact_dir;
     Buf output_file_path;
     Buf o_file_output_path;
-    Buf *wanted_output_file_path;
     Buf *cache_dir;
+    // As an input parameter, mutually exclusive with enable_cache. But it gets
+    // populated in codegen_build_and_link.
+    Buf *output_dir;
     Buf **libc_include_dir_list;
     size_t libc_include_dir_len;
 
@@ -1804,7 +1802,7 @@ struct CodeGen {
     bool verbose_cc;
     bool error_during_imports;
     bool generate_error_name_table;
-    bool enable_cache;
+    bool enable_cache; // mutually exclusive with output_dir
     bool enable_time_report;
     bool system_linker_hack;
     bool reported_bad_link_libc_error;
@@ -1844,6 +1842,7 @@ struct CodeGen {
     bool each_lib_rpath;
     bool disable_pic;
     bool is_dummy_so;
+    bool disable_gen_h;
 
     Buf *mmacosx_version_min;
     Buf *mios_version_min;
diff --git a/src/analyze.cpp b/src/analyze.cpp
index 366bb2963e..6cbcc311ef 100644
--- a/src/analyze.cpp
+++ b/src/analyze.cpp
@@ -35,20 +35,6 @@ static bool is_top_level_struct(ZigType *import) {
 static ErrorMsg *add_error_note_token(CodeGen *g, ErrorMsg *parent_msg, ZigType *owner, Token *token, Buf *msg) {
     assert(is_top_level_struct(owner));
     RootStruct *root_struct = owner->data.structure.root_struct;
-    if (root_struct->c_import_node != nullptr) {
-        // if this happens, then translate_c generated code that
-        // failed semantic analysis, which isn't supposed to happen
-
-        Buf *note_path = buf_create_from_str("?.c");
-        Buf *note_source = buf_create_from_str("TODO: remember C source location to display here ");
-        ZigList<size_t> note_line_offsets = {0};
-        note_line_offsets.append(0);
-        ErrorMsg *note = err_msg_create_with_line(note_path, 0, 0,
-                note_source, &note_line_offsets, msg);
-
-        err_msg_add_note(parent_msg, note);
-        return note;
-    }
 
     ErrorMsg *err = err_msg_create_with_line(root_struct->path, token->start_line, token->start_column,
             root_struct->source_code, root_struct->line_offsets, msg);
@@ -60,17 +46,6 @@ static ErrorMsg *add_error_note_token(CodeGen *g, ErrorMsg *parent_msg, ZigType
 ErrorMsg *add_token_error(CodeGen *g, ZigType *owner, Token *token, Buf *msg) {
     assert(is_top_level_struct(owner));
     RootStruct *root_struct = owner->data.structure.root_struct;
-    if (root_struct->c_import_node != nullptr) {
-        // if this happens, then translate_c generated code that
-        // failed semantic analysis, which isn't supposed to happen
-        ErrorMsg *err = add_node_error(g, root_struct->c_import_node,
-            buf_sprintf("compiler bug: @cImport generated invalid zig code"));
-
-        add_error_note_token(g, err, owner, token, msg);
-
-        g->errors.append(err);
-        return err;
-    }
     ErrorMsg *err = err_msg_create_with_line(root_struct->path, token->start_line, token->start_column,
             root_struct->source_code, root_struct->line_offsets, msg);
 
@@ -1300,7 +1275,7 @@ static ZigTypeId container_to_type(ContainerKind kind) {
 }
 
 // This is like get_partial_container_type except it's for the implicit root struct of files.
-ZigType *get_root_container_type(CodeGen *g, const char *full_name, Buf *bare_name,
+static ZigType *get_root_container_type(CodeGen *g, const char *full_name, Buf *bare_name,
         RootStruct *root_struct)
 {
     ZigType *entry = new_type_table_entry(ZigTypeIdStruct);
@@ -4503,11 +4478,11 @@ ZigType *add_source_file(CodeGen *g, ZigPackage *package, Buf *resolved_path, Bu
     Buf *pkg_root_src_dir = &package->root_src_dir;
     Buf resolved_root_src_dir = os_path_resolve(&pkg_root_src_dir, 1);
 
-    assert(buf_starts_with_buf(resolved_path, &resolved_root_src_dir));
-
     Buf namespace_name = BUF_INIT;
     buf_init_from_buf(&namespace_name, &package->pkg_path);
     if (source_kind == SourceKindNonRoot) {
+        assert(buf_starts_with_buf(resolved_path, &resolved_root_src_dir));
+
         if (buf_len(&namespace_name) != 0) buf_append_char(&namespace_name, NAMESPACE_SEP_CHAR);
         buf_append_mem(&namespace_name, buf_ptr(&noextname) + buf_len(&resolved_root_src_dir) + 1,
             buf_len(&noextname) - (buf_len(&resolved_root_src_dir) + 1));
diff --git a/src/analyze.hpp b/src/analyze.hpp
index aa94f0c2c5..22e44ebd3f 100644
--- a/src/analyze.hpp
+++ b/src/analyze.hpp
@@ -31,8 +31,6 @@ ZigType *get_array_type(CodeGen *g, ZigType *child_type, uint64_t array_size);
 ZigType *get_slice_type(CodeGen *g, ZigType *ptr_type);
 ZigType *get_partial_container_type(CodeGen *g, Scope *scope, ContainerKind kind,
         AstNode *decl_node, const char *full_name, Buf *bare_name, ContainerLayout layout);
-ZigType *get_root_container_type(CodeGen *g, const char *full_name, Buf *bare_name,
-        RootStruct *root_struct);
 ZigType *get_smallest_unsigned_int_type(CodeGen *g, uint64_t x);
 ZigType *get_error_union_type(CodeGen *g, ZigType *err_set_type, ZigType *payload_type);
 ZigType *get_bound_fn_type(CodeGen *g, ZigFn *fn_entry);
@@ -53,6 +51,7 @@ enum SourceKind {
     SourceKindRoot,
     SourceKindPkgMain,
     SourceKindNonRoot,
+    SourceKindCImport,
 };
 ZigType *add_source_file(CodeGen *g, ZigPackage *package, Buf *abs_full_path, Buf *source_code,
         SourceKind source_kind);
@@ -242,4 +241,6 @@ Error ensure_const_val_repr(IrAnalyze *ira, CodeGen *codegen, AstNode *source_no
 void typecheck_panic_fn(CodeGen *g, TldFn *tld_fn, ZigFn *panic_fn);
 Buf *type_bare_name(ZigType *t);
 Buf *type_h_name(ZigType *t);
+Error create_c_object_cache(CodeGen *g, CacheHash **out_cache_hash, bool verbose);
+
 #endif
diff --git a/src/ast_render.cpp b/src/ast_render.cpp
index 7b57841205..76a0622058 100644
--- a/src/ast_render.cpp
+++ b/src/ast_render.cpp
@@ -470,6 +470,9 @@ static void render_node_extra(AstRender *ar, AstNode *node, bool grouped) {
                         fprintf(ar->f, ", ");
                     }
                 }
+                if (node->data.fn_proto.is_var_args) {
+                    fprintf(ar->f, ", ...");
+                }
                 fprintf(ar->f, ")");
                 if (node->data.fn_proto.align_expr) {
                     fprintf(ar->f, " align(");
diff --git a/src/cache_hash.cpp b/src/cache_hash.cpp
index e9d4bdc671..cd336b71ae 100644
--- a/src/cache_hash.cpp
+++ b/src/cache_hash.cpp
@@ -19,6 +19,8 @@ void cache_init(CacheHash *ch, Buf *manifest_dir) {
     ch->manifest_dir = manifest_dir;
     ch->manifest_file_path = nullptr;
     ch->manifest_dirty = false;
+    ch->force_check_manifest = false;
+    ch->b64_digest = BUF_INIT;
 }
 
 void cache_str(CacheHash *ch, const char *ptr) {
@@ -243,22 +245,21 @@ Error cache_hit(CacheHash *ch, Buf *out_digest) {
     int rc = blake2b_final(&ch->blake, bin_digest, 48);
     assert(rc == 0);
 
-    if (ch->files.length == 0) {
+    buf_resize(&ch->b64_digest, 64);
+    base64_encode(buf_to_slice(&ch->b64_digest), {bin_digest, 48});
+
+    if (ch->files.length == 0 && !ch->force_check_manifest) {
         buf_resize(out_digest, 64);
         base64_encode(buf_to_slice(out_digest), {bin_digest, 48});
         return ErrorNone;
     }
 
-    Buf b64_digest = BUF_INIT;
-    buf_resize(&b64_digest, 64);
-    base64_encode(buf_to_slice(&b64_digest), {bin_digest, 48});
-
     rc = blake2b_init(&ch->blake, 48);
     assert(rc == 0);
     blake2b_update(&ch->blake, bin_digest, 48);
 
     ch->manifest_file_path = buf_alloc();
-    os_path_join(ch->manifest_dir, &b64_digest, ch->manifest_file_path);
+    os_path_join(ch->manifest_dir, &ch->b64_digest, ch->manifest_file_path);
 
     buf_append_str(ch->manifest_file_path, ".txt");
 
@@ -380,7 +381,7 @@ Error cache_hit(CacheHash *ch, Buf *out_digest) {
             blake2b_update(&ch->blake, chf->bin_digest, 48);
         }
     }
-    if (file_i < input_file_count) {
+    if (file_i < input_file_count || file_i == 0) {
         // manifest file is empty or missing entries, so this is a cache miss
         ch->manifest_dirty = true;
         for (; file_i < input_file_count; file_i += 1) {
@@ -442,6 +443,7 @@ Error cache_add_dep_file(CacheHash *ch, Buf *dep_file_path, bool verbose) {
         }
         if (opt_line.value.len == 0)
             continue;
+
         if (opt_line.value.ptr[0] == '"') {
             if (opt_line.value.len < 2) {
                 if (verbose) {
@@ -460,21 +462,28 @@ Error cache_add_dep_file(CacheHash *ch, Buf *dep_file_path, bool verbose) {
                 }
                 return ErrorInvalidDepFile;
             }
+            Buf *filename_buf = buf_create_from_slice(opt_line.value);
+            if ((err = cache_add_file(ch, filename_buf))) {
+                if (verbose) {
+                    fprintf(stderr, "unable to add %s to cache: %s\n", buf_ptr(filename_buf), err_str(err));
+                    fprintf(stderr, "when processing .d file: %s\n", buf_ptr(dep_file_path));
+                }
+                return err;
+            }
         } else {
-            if (opt_line.value.ptr[opt_line.value.len - 1] == '\\') {
-                opt_line.value.len -= 2; // cut off ` \`
+            // sometimes there are multiple files on the same line; we actually need space tokenization.
+            SplitIterator line_it = memSplit(opt_line.value, str(" \t\\"));
+            Slice<uint8_t> filename;
+            while (SplitIterator_next(&line_it).unwrap(&filename)) {
+                Buf *filename_buf = buf_create_from_slice(filename);
+                if ((err = cache_add_file(ch, filename_buf))) {
+                    if (verbose) {
+                        fprintf(stderr, "unable to add %s to cache: %s\n", buf_ptr(filename_buf), err_str(err));
+                        fprintf(stderr, "when processing .d file: %s\n", buf_ptr(dep_file_path));
+                    }
+                    return err;
+                }
             }
-            if (opt_line.value.len == 0)
-                continue;
-        }
-
-        Buf *filename_buf = buf_create_from_slice(opt_line.value);
-        if ((err = cache_add_file(ch, filename_buf))) {
-            if (verbose) {
-                fprintf(stderr, "unable to add %s to cache: %s\n", buf_ptr(filename_buf), err_str(err));
-                fprintf(stderr, "when processing .d file: %s\n", buf_ptr(dep_file_path));
-            }
-            return err;
         }
     }
     return ErrorNone;
diff --git a/src/cache_hash.hpp b/src/cache_hash.hpp
index d74c8623ce..5be02ea405 100644
--- a/src/cache_hash.hpp
+++ b/src/cache_hash.hpp
@@ -25,8 +25,10 @@ struct CacheHash {
     ZigList<CacheHashFile> files;
     Buf *manifest_dir;
     Buf *manifest_file_path;
+    Buf b64_digest;
     OsFile manifest_file;
     bool manifest_dirty;
+    bool force_check_manifest;
 };
 
 // Always call this first to set up.
@@ -51,6 +53,10 @@ void cache_file_opt(CacheHash *ch, Buf *path);
 // If you got a cache hit, the next step is cache_release.
 // From this point on, there is a lock on the input params. Release
 // the lock with cache_release.
+// Set force_check_manifest if you plan to add files later, but have not
+// added any files before calling cache_hit. CacheHash::b64_digest becomes
+// available for use after this call, even in the case of a miss, and it
+// is a hash of the input parameters only.
 Error ATTRIBUTE_MUST_USE cache_hit(CacheHash *ch, Buf *out_b64_digest);
 
 // If you did not get a cache hit, call this function for every file
diff --git a/src/codegen.cpp b/src/codegen.cpp
index 87974b7778..30b1c87662 100644
--- a/src/codegen.cpp
+++ b/src/codegen.cpp
@@ -23,6 +23,9 @@
 #include <stdio.h>
 #include <errno.h>
 
+#define CACHE_OUT_SUBDIR "o"
+#define CACHE_HASH_SUBDIR "h"
+
 static void init_darwin_native(CodeGen *g) {
     char *osx_target = getenv("MACOSX_DEPLOYMENT_TARGET");
     char *ios_target = getenv("IPHONEOS_DEPLOYMENT_TARGET");
@@ -196,18 +199,6 @@ CodeGen *codegen_create(Buf *main_pkg_path, Buf *root_src_path, const ZigTarget
     return g;
 }
 
-void codegen_set_output_h_path(CodeGen *g, Buf *h_path) {
-    g->out_h_path = h_path;
-}
-
-void codegen_set_output_lib_path(CodeGen *g, Buf *lib_path) {
-    g->out_lib_path = lib_path;
-}
-
-void codegen_set_output_path(CodeGen *g, Buf *path) {
-    g->wanted_output_file_path = path;
-}
-
 void codegen_set_clang_argv(CodeGen *g, const char **args, size_t len) {
     g->clang_argv = args;
     g->clang_argv_len = len;
@@ -256,10 +247,6 @@ void codegen_set_out_name(CodeGen *g, Buf *out_name) {
     g->root_out_name = out_name;
 }
 
-void codegen_set_dynamic_linker(CodeGen *g, Buf *dynamic_linker_path) {
-    g->dynamic_linker_path = dynamic_linker_path;
-}
-
 void codegen_add_lib_dir(CodeGen *g, const char *dir) {
     g->lib_dirs.append(dir);
 }
@@ -7766,7 +7753,10 @@ static Error define_builtin_compile_vars(CodeGen *g) {
         }
     } else {
         contents = codegen_generate_builtin_source(g);
-        os_write_file(builtin_zig_path, contents);
+        if ((err = os_write_file(builtin_zig_path, contents))) {
+            fprintf(stderr, "Unable to write file '%s': %s\n", buf_ptr(builtin_zig_path), err_str(err));
+            exit(1);
+        }
     }
 
     assert(g->root_package);
@@ -8030,7 +8020,7 @@ static void detect_libc(CodeGen *g) {
     }
 }
 
-void codegen_translate_c(CodeGen *g, Buf *full_path) {
+AstNode *codegen_translate_c(CodeGen *g, Buf *full_path) {
     Buf *src_basename = buf_alloc();
     Buf *src_dirname = buf_alloc();
     os_path_split(full_path, src_dirname, src_basename);
@@ -8042,16 +8032,9 @@ void codegen_translate_c(CodeGen *g, Buf *full_path) {
 
     init(g);
 
-    RootStruct *root_struct = allocate<RootStruct>(1);
-    root_struct->source_code = nullptr;
-    root_struct->path = full_path;
-    root_struct->di_file = ZigLLVMCreateFile(g->dbuilder, buf_ptr(src_basename), buf_ptr(src_dirname));
-
-    ZigType *import = get_root_container_type(g, buf_ptr(&noextname), &noextname, root_struct);
-    g->root_import = import;
-
     ZigList<ErrorMsg *> errors = {0};
-    Error err = parse_h_file(import, &errors, buf_ptr(full_path), g, nullptr);
+    AstNode *root_node;
+    Error err = parse_h_file(&root_node, &errors, buf_ptr(full_path), g, nullptr);
 
     if (err == ErrorCCompileErrors && errors.length > 0) {
         for (size_t i = 0; i < errors.length; i += 1) {
@@ -8065,6 +8048,8 @@ void codegen_translate_c(CodeGen *g, Buf *full_path) {
         fprintf(stderr, "unable to parse C file: %s\n", err_str(err));
         exit(1);
     }
+
+    return root_node;
 }
 
 static ZigType *add_special_code(CodeGen *g, ZigPackage *package, const char *basename) {
@@ -8282,32 +8267,18 @@ static Error get_tmp_filename(CodeGen *g, Buf *out, Buf *suffix) {
     return ErrorNone;
 }
 
-// returns true if it was a cache miss
-static void gen_c_object(CodeGen *g, Buf *self_exe_path, CFile *c_file) {
+Error create_c_object_cache(CodeGen *g, CacheHash **out_cache_hash, bool verbose) {
     Error err;
-
-    Buf *artifact_dir;
-    Buf *o_final_path;
-
-    Buf *o_dir = buf_alloc();
-    os_path_join(g->cache_dir, buf_create_from_str("o"), o_dir);
-
-    Buf *c_source_file = buf_create_from_str(c_file->source_path);
-    Buf *c_source_basename = buf_alloc();
-    os_path_split(c_source_file, nullptr, c_source_basename);
-    Buf *final_o_basename = buf_alloc();
-    os_path_extname(c_source_basename, final_o_basename, nullptr);
-    buf_append_str(final_o_basename, target_o_file_ext(g->zig_target));
-
     CacheHash *cache_hash = allocate<CacheHash>(1);
-    Buf *manifest_dir = buf_alloc();
-    os_path_join(g->cache_dir, buf_create_from_str("c"), manifest_dir);
+    Buf *manifest_dir = buf_sprintf("%s" OS_SEP CACHE_HASH_SUBDIR, buf_ptr(g->cache_dir));
     cache_init(cache_hash, manifest_dir);
 
     Buf *compiler_id;
     if ((err = get_compiler_id(&compiler_id))) {
-        fprintf(stderr, "unable to get compiler id: %s\n", err_str(err));
-        exit(1);
+        if (verbose) {
+            fprintf(stderr, "unable to get compiler id: %s\n", err_str(err));
+        }
+        return err;
     }
     cache_buf(cache_hash, compiler_id);
     cache_int(cache_hash, g->err_color);
@@ -8321,11 +8292,38 @@ static void gen_c_object(CodeGen *g, Buf *self_exe_path, CFile *c_file) {
     cache_int(cache_hash, g->zig_target->abi);
     cache_bool(cache_hash, g->strip_debug_symbols);
     cache_int(cache_hash, g->build_mode);
-    cache_file(cache_hash, c_source_file);
     cache_bool(cache_hash, g->disable_pic);
     for (size_t arg_i = 0; arg_i < g->clang_argv_len; arg_i += 1) {
         cache_str(cache_hash, g->clang_argv[arg_i]);
     }
+
+    *out_cache_hash = cache_hash;
+    return ErrorNone;
+}
+
+// returns true if it was a cache miss
+static void gen_c_object(CodeGen *g, Buf *self_exe_path, CFile *c_file) {
+    Error err;
+
+    Buf *artifact_dir;
+    Buf *o_final_path;
+
+    Buf *o_dir = buf_sprintf("%s" OS_SEP CACHE_OUT_SUBDIR, buf_ptr(g->cache_dir));
+
+    Buf *c_source_file = buf_create_from_str(c_file->source_path);
+    Buf *c_source_basename = buf_alloc();
+    os_path_split(c_source_file, nullptr, c_source_basename);
+    Buf *final_o_basename = buf_alloc();
+    os_path_extname(c_source_basename, final_o_basename, nullptr);
+    buf_append_str(final_o_basename, target_o_file_ext(g->zig_target));
+
+    CacheHash *cache_hash;
+    if ((err = create_c_object_cache(g, &cache_hash, true))) {
+        // Already printed error; verbose = true
+        exit(1);
+    }
+    cache_file(cache_hash, c_source_file);
+
     // Note: not directory args, just args that always have a file next
     static const char *file_args[] = {
         "-include",
@@ -8787,11 +8785,13 @@ static void gen_h_file(CodeGen *g) {
     GenH *gen_h = &gen_h_data;
 
     assert(!g->is_test_build);
-    assert(g->out_h_path != nullptr);
+    assert(!g->disable_gen_h);
 
-    FILE *out_h = fopen(buf_ptr(g->out_h_path), "wb");
+    Buf *out_h_path = buf_sprintf("%s" OS_SEP "%s.h", buf_ptr(g->output_dir), buf_ptr(g->root_out_name));
+
+    FILE *out_h = fopen(buf_ptr(out_h_path), "wb");
     if (!out_h)
-        zig_panic("unable to open %s: %s\n", buf_ptr(g->out_h_path), strerror(errno));
+        zig_panic("unable to open %s: %s\n", buf_ptr(out_h_path), strerror(errno));
 
     Buf *export_macro = preprocessor_mangle(buf_sprintf("%s_EXPORT", buf_ptr(g->root_out_name)));
     buf_upcase(export_macro);
@@ -9065,6 +9065,7 @@ static Error check_cache(CodeGen *g, Buf *manifest_dir, Buf *digest) {
     cache_bool(ch, g->linker_rdynamic);
     cache_bool(ch, g->each_lib_rpath);
     cache_bool(ch, g->disable_pic);
+    cache_bool(ch, g->disable_gen_h);
     cache_bool(ch, g->valgrind_support);
     cache_bool(ch, g->is_dummy_so);
     cache_buf_opt(ch, g->mmacosx_version_min);
@@ -9103,99 +9104,83 @@ static bool need_llvm_module(CodeGen *g) {
     return g->assembly_files.length != 0 || buf_len(&g->root_package->root_src_path) != 0;
 }
 
-static bool compilation_is_already_done(CodeGen *g) {
-    return !need_llvm_module(g) && g->link_objects.length == 1 && g->out_type == OutTypeObj;
-}
-
 static void resolve_out_paths(CodeGen *g) {
-    Buf *o_basename = buf_create_from_buf(g->root_out_name);
+    assert(g->output_dir != nullptr);
+    assert(g->root_out_name != nullptr);
 
+    Buf *out_basename = buf_create_from_buf(g->root_out_name);
+    Buf *o_basename = buf_create_from_buf(g->root_out_name);
     switch (g->emit_file_type) {
-        case EmitFileTypeBinary:
-        {
-            const char *o_ext = target_o_file_ext(g->zig_target);
-            buf_append_str(o_basename, o_ext);
+        case EmitFileTypeBinary: {
+            switch (g->out_type) {
+                case OutTypeUnknown:
+                    zig_unreachable();
+                case OutTypeObj:
+                    if (g->enable_cache && g->link_objects.length == 1 && !need_llvm_module(g)) {
+                        buf_init_from_buf(&g->output_file_path, g->link_objects.at(0));
+                        return;
+                    }
+                    if (!need_llvm_module(g) || (g->enable_cache && g->link_objects.length == 0)) {
+                        // Either we're not creating an object file from our LLVM Module,
+                        // or we have caching enabled and do not need to link objects together.
+                        // In both cases, the output file path and object file path basename can match.
+                        buf_append_str(o_basename, target_o_file_ext(g->zig_target));
+                        buf_append_str(out_basename, target_o_file_ext(g->zig_target));
+                    } else {
+                        // make it not collide with main output object
+                        buf_append_str(o_basename, ".root");
+                        buf_append_str(o_basename, target_o_file_ext(g->zig_target));
+                        buf_append_str(out_basename, target_o_file_ext(g->zig_target));
+                    }
+                    break;
+                case OutTypeExe:
+                    buf_append_str(o_basename, target_o_file_ext(g->zig_target));
+                    buf_append_str(out_basename, target_exe_file_ext(g->zig_target));
+                    break;
+                case OutTypeLib:
+                    buf_append_str(o_basename, target_o_file_ext(g->zig_target));
+                    buf_resize(out_basename, 0);
+                    buf_append_str(out_basename, target_lib_file_prefix(g->zig_target));
+                    buf_append_buf(out_basename, g->root_out_name);
+                    buf_append_str(out_basename, target_lib_file_ext(g->zig_target, g->is_static,
+                                g->version_major, g->version_minor, g->version_patch));
+                    break;
+            }
             break;
         }
-        case EmitFileTypeAssembly:
-        {
+        case EmitFileTypeAssembly: {
             const char *asm_ext = target_asm_file_ext(g->zig_target);
             buf_append_str(o_basename, asm_ext);
+            buf_append_str(out_basename, asm_ext);
             break;
         }
-        case EmitFileTypeLLVMIr:
-        {
+        case EmitFileTypeLLVMIr: {
             const char *llvm_ir_ext = target_llvm_ir_file_ext(g->zig_target);
             buf_append_str(o_basename, llvm_ir_ext);
+            buf_append_str(out_basename, llvm_ir_ext);
             break;
         }
-        default:
-            zig_unreachable();
     }
 
-    if (compilation_is_already_done(g)) {
-        buf_init_from_str(&g->o_file_output_path, buf_ptr(g->link_objects.at(0)));
-    } else if (g->enable_cache || g->out_type != OutTypeObj) {
-        os_path_join(&g->artifact_dir, o_basename, &g->o_file_output_path);
-    } else if (g->wanted_output_file_path != nullptr && g->out_type == OutTypeObj) {
-        buf_init_from_buf(&g->o_file_output_path, g->wanted_output_file_path);
-    } else {
-        buf_init_from_buf(&g->o_file_output_path, o_basename);
-    }
-
-    if (!g->enable_cache && g->wanted_output_file_path != nullptr) {
-        buf_init_from_buf(&g->output_file_path, g->wanted_output_file_path);
-        return;
-    }
-
-    if (compilation_is_already_done(g)) {
-        buf_init_from_buf(&g->output_file_path, &g->o_file_output_path);
-        return;
-    }
-
-    const char *prefix = "";
-    const char *extname;
-    switch (g->out_type) {
-        case OutTypeUnknown:
-            zig_unreachable();
-        case OutTypeObj:
-            extname = target_o_file_ext(g->zig_target);
-            break;
-        case OutTypeExe:
-            extname = target_exe_file_ext(g->zig_target);
-            break;
-        case OutTypeLib:
-            prefix = target_lib_file_prefix(g->zig_target);
-            extname = target_lib_file_ext(g->zig_target, g->is_static,
-                        g->version_major, g->version_minor, g->version_patch);
-            break;
-    }
-
-    assert(g->root_out_name);
-
-    Buf basename = BUF_INIT;
-    buf_init_from_str(&basename, prefix);
-    buf_append_buf(&basename, g->root_out_name);
-    buf_append_str(&basename, extname);
-    if (g->enable_cache || g->is_test_build) {
-        os_path_join(&g->artifact_dir, &basename, &g->output_file_path);
-    } else {
-        buf_init_from_buf(&g->output_file_path, &basename);
-    }
+    os_path_join(g->output_dir, o_basename, &g->o_file_output_path);
+    os_path_join(g->output_dir, out_basename, &g->output_file_path);
 }
 
 void codegen_build_and_link(CodeGen *g) {
     Error err;
     assert(g->out_type != OutTypeUnknown);
 
+    if (!g->enable_cache && g->output_dir == nullptr) {
+        g->output_dir = buf_create_from_str(".");
+    }
+
     detect_libc(g);
     detect_dynamic_linker(g);
 
-    Buf *artifact_dir = buf_alloc();
     Buf digest = BUF_INIT;
     if (g->enable_cache) {
         Buf *manifest_dir = buf_alloc();
-        os_path_join(g->cache_dir, buf_create_from_str("h"), manifest_dir);
+        os_path_join(g->cache_dir, buf_create_from_str(CACHE_HASH_SUBDIR), manifest_dir);
 
         if ((err = check_cache(g, manifest_dir, &digest))) {
             if (err == ErrorCacheUnavailable) {
@@ -9208,15 +9193,14 @@ void codegen_build_and_link(CodeGen *g) {
             }
             exit(1);
         }
-
-        os_path_join(g->cache_dir, buf_create_from_str("artifact"), artifact_dir);
     } else {
         // There is a call to this in check_cache
         gen_c_objects(g);
     }
 
     if (g->enable_cache && buf_len(&digest) != 0) {
-        os_path_join(artifact_dir, &digest, &g->artifact_dir);
+        g->output_dir = buf_sprintf("%s" OS_SEP CACHE_OUT_SUBDIR OS_SEP "%s",
+                buf_ptr(g->cache_dir), buf_ptr(&digest));
         resolve_out_paths(g);
     } else {
         if (need_llvm_module(g)) {
@@ -9235,13 +9219,13 @@ void codegen_build_and_link(CodeGen *g) {
                     exit(1);
                 }
             }
-            os_path_join(artifact_dir, &digest, &g->artifact_dir);
-        } else {
-            buf_init_from_buf(&g->artifact_dir, g->cache_dir);
-        }
-        if ((err = os_make_path(&g->artifact_dir))) {
-            fprintf(stderr, "Unable to create artifact directory: %s\n", err_str(err));
-            exit(1);
+            g->output_dir = buf_sprintf("%s" OS_SEP CACHE_OUT_SUBDIR OS_SEP "%s",
+                    buf_ptr(g->cache_dir), buf_ptr(&digest));
+
+            if ((err = os_make_path(g->output_dir))) {
+                fprintf(stderr, "Unable to create output directory: %s\n", err_str(err));
+                exit(1);
+            }
         }
         resolve_out_paths(g);
 
@@ -9252,14 +9236,19 @@ void codegen_build_and_link(CodeGen *g) {
             codegen_add_time_event(g, "LLVM Emit Output");
             zig_llvm_emit_output(g);
 
-            if (g->out_h_path != nullptr) {
+            if (!g->disable_gen_h && (g->out_type == OutTypeObj || g->out_type == OutTypeLib)) {
                 codegen_add_time_event(g, "Generate .h");
                 gen_h_file(g);
             }
         }
 
-        if (g->emit_file_type == EmitFileTypeBinary &&
-            (g->link_objects.length > 1 || g->out_type != OutTypeObj))
+        // If we're outputting assembly or llvm IR we skip linking.
+        // If we're making a library or executable we must link.
+        // If there is more than one object, we have to link them (with -r).
+        // Finally, if we didn't make an object from zig source, and we don't have caching enabled,
+        // then we have an object from C source that we must copy to the output dir which we do with a -r link.
+        if (g->emit_file_type == EmitFileTypeBinary && (g->out_type != OutTypeObj || g->link_objects.length > 1 ||
+                    (!need_llvm_module(g) && !g->enable_cache)))
         {
             codegen_link(g);
         }
diff --git a/src/codegen.hpp b/src/codegen.hpp
index 120b68bb11..3befca2de5 100644
--- a/src/codegen.hpp
+++ b/src/codegen.hpp
@@ -28,7 +28,6 @@ void codegen_set_emit_file_type(CodeGen *g, EmitFileType emit_file_type);
 void codegen_set_strip(CodeGen *codegen, bool strip);
 void codegen_set_errmsg_color(CodeGen *codegen, ErrColor err_color);
 void codegen_set_out_name(CodeGen *codegen, Buf *out_name);
-void codegen_set_dynamic_linker(CodeGen *g, Buf *dynamic_linker);
 void codegen_add_lib_dir(CodeGen *codegen, const char *dir);
 void codegen_add_forbidden_lib(CodeGen *codegen, Buf *lib);
 LinkLib *codegen_add_link_lib(CodeGen *codegen, Buf *lib);
@@ -41,9 +40,6 @@ void codegen_set_linker_script(CodeGen *g, const char *linker_script);
 void codegen_set_test_filter(CodeGen *g, Buf *filter);
 void codegen_set_test_name_prefix(CodeGen *g, Buf *prefix);
 void codegen_set_lib_version(CodeGen *g, size_t major, size_t minor, size_t patch);
-void codegen_set_output_h_path(CodeGen *g, Buf *h_path);
-void codegen_set_output_lib_path(CodeGen *g, Buf *lib_path);
-void codegen_set_output_path(CodeGen *g, Buf *path);
 void codegen_add_time_event(CodeGen *g, const char *name);
 void codegen_print_timing_report(CodeGen *g, FILE *f);
 void codegen_link(CodeGen *g);
@@ -54,7 +50,7 @@ ZigPackage *codegen_create_package(CodeGen *g, const char *root_src_dir, const c
 void codegen_add_assembly(CodeGen *g, Buf *path);
 void codegen_add_object(CodeGen *g, Buf *object_path);
 
-void codegen_translate_c(CodeGen *g, Buf *path);
+AstNode *codegen_translate_c(CodeGen *g, Buf *path);
 
 Buf *codegen_generate_builtin_source(CodeGen *g);
 
diff --git a/src/ir.cpp b/src/ir.cpp
index aeb03397ca..a8771285f6 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -16,6 +16,8 @@
 #include "translate_c.hpp"
 #include "util.hpp"
 
+#include <errno.h>
+
 struct IrExecContext {
     ZigList<ConstExprValue *> mem_slot_list;
 };
@@ -18687,7 +18689,15 @@ static IrInstruction *ir_analyze_instruction_type_name(IrAnalyze *ira, IrInstruc
     return result;
 }
 
+static void ir_cimport_cache_paths(Buf *cache_dir, Buf *tmp_c_file_digest, Buf *out_zig_dir, Buf *out_zig_path) {
+    buf_resize(out_zig_dir, 0);
+    buf_resize(out_zig_path, 0);
+    buf_appendf(out_zig_dir, "%s" OS_SEP "o" OS_SEP "%s",
+            buf_ptr(cache_dir), buf_ptr(tmp_c_file_digest));
+    buf_appendf(out_zig_path, "%s" OS_SEP "cimport.zig", buf_ptr(out_zig_dir));
+}
 static IrInstruction *ir_analyze_instruction_c_import(IrAnalyze *ira, IrInstructionCImport *instruction) {
+    Error err;
     AstNode *node = instruction->base.source_node;
     assert(node->type == NodeTypeFnCallExpr);
     AstNode *block_node = node->data.fn_call_expr.params.at(0);
@@ -18706,50 +18716,128 @@ static IrInstruction *ir_analyze_instruction_c_import(IrAnalyze *ira, IrInstruct
     Buf *namespace_name = buf_sprintf("%s.cimport:%" ZIG_PRI_usize ":%" ZIG_PRI_usize,
             buf_ptr(&cur_scope_pkg->pkg_path), node->line + 1, node->column + 1);
 
-    RootStruct *root_struct = allocate<RootStruct>(1);
-    root_struct->package = new_anonymous_package();
-    root_struct->package->package_table.put(buf_create_from_str("builtin"), ira->codegen->compile_var_package);
-    root_struct->package->package_table.put(buf_create_from_str("std"), ira->codegen->std_package);
-    root_struct->c_import_node = node;
-    // TODO create namespace_name file in zig-cache instead of /tmp and use it
-    // for this DIFile
-    root_struct->di_file = ZigLLVMCreateFile(ira->codegen->dbuilder,
-        buf_ptr(buf_create_from_str("cimport.h")), buf_ptr(buf_create_from_str(".")));
-    ZigType *child_import = get_root_container_type(ira->codegen, buf_ptr(namespace_name),
-            namespace_name, root_struct);
-
-    ZigList<ErrorMsg *> errors = {0};
-
-    Error err;
-    if ((err = parse_h_buf(child_import, &errors, &cimport_scope->buf, ira->codegen, node))) {
-        if (err != ErrorCCompileErrors) {
-            ir_add_error_node(ira, node, buf_sprintf("C import failed: %s", err_str(err)));
-            return ira->codegen->invalid_instruction;
-        }
-    }
-
-    if (errors.length > 0) {
-        ErrorMsg *parent_err_msg = ir_add_error_node(ira, node, buf_sprintf("C import failed"));
-        if (ira->codegen->libc_link_lib == nullptr) {
-            add_error_note(ira->codegen, parent_err_msg, node,
-                buf_sprintf("libc headers not available; compilation does not link against libc"));
-        }
-        for (size_t i = 0; i < errors.length; i += 1) {
-            ErrorMsg *err_msg = errors.at(i);
-            err_msg_add_note(parent_err_msg, err_msg);
-        }
+    ZigPackage *cimport_pkg = new_anonymous_package();
+    cimport_pkg->package_table.put(buf_create_from_str("builtin"), ira->codegen->compile_var_package);
+    cimport_pkg->package_table.put(buf_create_from_str("std"), ira->codegen->std_package);
+    buf_init_from_buf(&cimport_pkg->pkg_path, namespace_name);
 
+    CacheHash *cache_hash;
+    if ((err = create_c_object_cache(ira->codegen, &cache_hash, false))) {
+        ir_add_error_node(ira, node, buf_sprintf("C import failed: unable to create cache: %s", err_str(err)));
         return ira->codegen->invalid_instruction;
     }
+    cache_buf(cache_hash, &cimport_scope->buf);
 
-    if (ira->codegen->verbose_cimport) {
-        fprintf(stderr, "\nC imports:\n");
-        fprintf(stderr, "-----------\n");
-        ast_render(ira->codegen, stderr, child_import->data.structure.decl_node, 4);
+    // Set this because we're not adding any files before checking for a hit.
+    cache_hash->force_check_manifest = true;
+
+    Buf tmp_c_file_digest = BUF_INIT;
+    buf_resize(&tmp_c_file_digest, 0);
+    if ((err = cache_hit(cache_hash, &tmp_c_file_digest))) {
+        ir_add_error_node(ira, node, buf_sprintf("C import failed: unable to check cache: %s", err_str(err)));
+        return ira->codegen->invalid_instruction;
+    }
+    ira->codegen->caches_to_release.append(cache_hash);
+
+    Buf *out_zig_dir = buf_alloc();
+    Buf *out_zig_path = buf_alloc();
+    if (buf_len(&tmp_c_file_digest) == 0 || cache_hash->files.length == 0) {
+        // Cache Miss
+        Buf *tmp_c_file_dir = buf_sprintf("%s" OS_SEP "o" OS_SEP "%s",
+                buf_ptr(ira->codegen->cache_dir), buf_ptr(&cache_hash->b64_digest));
+        Buf *resolve_paths[] = {
+            tmp_c_file_dir,
+            buf_create_from_str("cimport.h"),
+        };
+        Buf tmp_c_file_path = os_path_resolve(resolve_paths, 2);
+
+        if ((err = os_make_path(tmp_c_file_dir))) {
+            ir_add_error_node(ira, node, buf_sprintf("C import failed: unable to make dir: %s", err_str(err)));
+            return ira->codegen->invalid_instruction;
+        }
+        
+        if ((err = os_write_file(&tmp_c_file_path, &cimport_scope->buf))) {
+            ir_add_error_node(ira, node, buf_sprintf("C import failed: unable to write .h file: %s", err_str(err)));
+            return ira->codegen->invalid_instruction;
+        }
+        if (ira->codegen->verbose_cimport) {
+            fprintf(stderr, "@cImport source: %s\n", buf_ptr(&tmp_c_file_path));
+        }
+
+        ZigList<ErrorMsg *> errors = {0};
+
+        Buf *tmp_dep_file = buf_sprintf("%s.d", buf_ptr(&tmp_c_file_path));
+        AstNode *root_node;
+        if ((err = parse_h_file(&root_node, &errors, buf_ptr(&tmp_c_file_path), ira->codegen, tmp_dep_file))) {
+            if (err != ErrorCCompileErrors) {
+                ir_add_error_node(ira, node, buf_sprintf("C import failed: %s", err_str(err)));
+                return ira->codegen->invalid_instruction;
+            }
+            assert(errors.length > 0);
+
+            ErrorMsg *parent_err_msg = ir_add_error_node(ira, node, buf_sprintf("C import failed"));
+            if (ira->codegen->libc_link_lib == nullptr) {
+                add_error_note(ira->codegen, parent_err_msg, node,
+                    buf_sprintf("libc headers not available; compilation does not link against libc"));
+            }
+            for (size_t i = 0; i < errors.length; i += 1) {
+                ErrorMsg *err_msg = errors.at(i);
+                err_msg_add_note(parent_err_msg, err_msg);
+            }
+
+            return ira->codegen->invalid_instruction;
+        }
+        if (ira->codegen->verbose_cimport) {
+            fprintf(stderr, "@cImport .d file: %s\n", buf_ptr(tmp_dep_file));
+        }
+
+        if ((err = cache_add_dep_file(cache_hash, tmp_dep_file, false))) {
+            ir_add_error_node(ira, node, buf_sprintf("C import failed: unable to parse .d file: %s", err_str(err)));
+            return ira->codegen->invalid_instruction;
+        }
+        if ((err = cache_final(cache_hash, &tmp_c_file_digest))) {
+            ir_add_error_node(ira, node, buf_sprintf("C import failed: unable to finalize cache: %s", err_str(err)));
+            return ira->codegen->invalid_instruction;
+        }
+
+        ir_cimport_cache_paths(ira->codegen->cache_dir, &tmp_c_file_digest, out_zig_dir, out_zig_path);
+        if ((err = os_make_path(out_zig_dir))) {
+            ir_add_error_node(ira, node, buf_sprintf("C import failed: unable to make output dir: %s", err_str(err)));
+            return ira->codegen->invalid_instruction;
+        }
+        FILE *out_file = fopen(buf_ptr(out_zig_path), "wb");
+        if (out_file == nullptr) {
+            ir_add_error_node(ira, node,
+                    buf_sprintf("C import failed: unable to open output file: %s", strerror(errno)));
+            return ira->codegen->invalid_instruction;
+        }
+        ast_render(ira->codegen, out_file, root_node, 4);
+        if (fclose(out_file) != 0) {
+            ir_add_error_node(ira, node,
+                    buf_sprintf("C import failed: unable to write to output file: %s", strerror(errno)));
+            return ira->codegen->invalid_instruction;
+        }
+
+        if (ira->codegen->verbose_cimport) {
+            fprintf(stderr, "@cImport output: %s\n", buf_ptr(out_zig_path));
+        }
+
+    } else {
+        // Cache Hit
+        ir_cimport_cache_paths(ira->codegen->cache_dir, &tmp_c_file_digest, out_zig_dir, out_zig_path);
+        if (ira->codegen->verbose_cimport) {
+            fprintf(stderr, "@cImport cache hit: %s\n", buf_ptr(out_zig_path));
+        }
     }
 
-    scan_decls(ira->codegen, get_container_scope(child_import), child_import->data.structure.decl_node);
-
+    Buf *import_code = buf_alloc();
+    if ((err = file_fetch(ira->codegen, out_zig_path, import_code))) {
+        ir_add_error_node(ira, node,
+                buf_sprintf("unable to open '%s': %s", buf_ptr(out_zig_path), err_str(err)));
+        return ira->codegen->invalid_instruction;
+    }
+    ZigType *child_import = add_source_file(ira->codegen, cimport_pkg, out_zig_path,
+            import_code, SourceKindCImport);
     return ir_const_type(ira, &instruction->base, child_import);
 }
 
diff --git a/src/link.cpp b/src/link.cpp
index a8d01303aa..eee2224a48 100644
--- a/src/link.cpp
+++ b/src/link.cpp
@@ -24,7 +24,7 @@ static CodeGen *create_child_codegen(CodeGen *parent_gen, Buf *root_src_path, Ou
 {
     CodeGen *child_gen = codegen_create(nullptr, root_src_path, parent_gen->zig_target, out_type,
         parent_gen->build_mode, parent_gen->zig_lib_dir, parent_gen->zig_std_dir, libc, get_stage1_cache_path());
-    child_gen->out_h_path = nullptr;
+    child_gen->disable_gen_h = true;
     child_gen->verbose_tokenize = parent_gen->verbose_tokenize;
     child_gen->verbose_ast = parent_gen->verbose_ast;
     child_gen->verbose_link = parent_gen->verbose_link;
@@ -700,11 +700,8 @@ static void construct_linker_job_elf(LinkJob *lj) {
     } else if (is_dyn_lib) {
         lj->args.append("-shared");
 
-        if (buf_len(&g->output_file_path) == 0) {
-            buf_appendf(&g->output_file_path, "lib%s.so.%" ZIG_PRI_usize ".%" ZIG_PRI_usize ".%" ZIG_PRI_usize "",
-                    buf_ptr(g->root_out_name), g->version_major, g->version_minor, g->version_patch);
-        }
-        soname = buf_sprintf("lib%s.so.%" ZIG_PRI_usize "", buf_ptr(g->root_out_name), g->version_major);
+        assert(buf_len(&g->output_file_path) != 0);
+        soname = buf_sprintf("lib%s.so.%" ZIG_PRI_usize, buf_ptr(g->root_out_name), g->version_major);
     }
 
     lj->args.append("-o");
@@ -884,11 +881,6 @@ static void construct_linker_job_wasm(LinkJob *lj) {
     }
 }
 
-//static bool is_target_cyg_mingw(const ZigTarget *target) {
-//    return (target->os == ZigLLVM_Win32 && target->abi == ZigLLVM_Cygnus) ||
-//        (target->os == ZigLLVM_Win32 && target->abi == ZigLLVM_GNU);
-//}
-
 static void coff_append_machine_arg(CodeGen *g, ZigList<const char *> *list) {
     if (g->zig_target->arch == ZigLLVM_x86) {
         list->append("-MACHINE:X86");
@@ -960,6 +952,7 @@ static void add_nt_link_args(LinkJob *lj, bool is_library) {
 }
 
 static void construct_linker_job_coff(LinkJob *lj) {
+    Error err;
     CodeGen *g = lj->codegen;
 
     lj->args.append("/ERRORLIMIT:0");
@@ -1079,11 +1072,13 @@ static void construct_linker_job_coff(LinkJob *lj) {
             buf_appendf(def_contents, "\n");
 
             Buf *def_path = buf_alloc();
-            os_path_join(&g->artifact_dir, buf_sprintf("%s.def", buf_ptr(link_lib->name)), def_path);
-            os_write_file(def_path, def_contents);
+            os_path_join(g->output_dir, buf_sprintf("%s.def", buf_ptr(link_lib->name)), def_path);
+            if ((err = os_write_file(def_path, def_contents))) {
+                zig_panic("error writing def file: %s", err_str(err));
+            }
 
             Buf *generated_lib_path = buf_alloc();
-            os_path_join(&g->artifact_dir, buf_sprintf("%s.lib", buf_ptr(link_lib->name)), generated_lib_path);
+            os_path_join(g->output_dir, buf_sprintf("%s.lib", buf_ptr(link_lib->name)), generated_lib_path);
 
             gen_lib_args.resize(0);
             gen_lib_args.append("link");
@@ -1245,10 +1240,7 @@ static void construct_linker_job_macho(LinkJob *lj) {
         //lj->args.append("-install_name");
         //lj->args.append(buf_ptr(dylib_install_name));
 
-        if (buf_len(&g->output_file_path) == 0) {
-            buf_appendf(&g->output_file_path, "lib%s.%" ZIG_PRI_usize ".%" ZIG_PRI_usize ".%" ZIG_PRI_usize ".dylib",
-                buf_ptr(g->root_out_name), g->version_major, g->version_minor, g->version_patch);
-        }
+        assert(buf_len(&g->output_file_path) != 0);
     }
 
     lj->args.append("-arch");
diff --git a/src/main.cpp b/src/main.cpp
index cd1b9d2891..28da1cbbe7 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -48,9 +48,10 @@ static int print_full_usage(const char *arg0, FILE *file, int return_code) {
         "Compile Options:\n"
         "  --assembly [source]          add assembly file to build\n"
         "  --c-source [options] [file]  compile C source code\n"
-        "  --cache-dir [path]           override the cache directory\n"
-        "  --cache [auto|off|on]        build in global cache, print out paths to stdout\n"
+        "  --cache-dir [path]           override the local cache directory\n"
+        "  --cache [auto|off|on]        build in cache, print output path to stdout\n"
         "  --color [auto|off|on]        enable or disable colored error messages\n"
+        "  --disable-gen-h              do not generate a C header file (.h)\n"
         "  --disable-pic                disable Position Independent Code for libraries\n"
         "  --disable-valgrind           omit valgrind client requests in debug builds\n"
         "  --enable-valgrind            include valgrind client requests release builds\n"
@@ -58,9 +59,7 @@ static int print_full_usage(const char *arg0, FILE *file, int return_code) {
         "  -ftime-report                print timing diagnostics\n"
         "  --libc [file]                Provide a file which specifies libc paths\n"
         "  --name [name]                override output name\n"
-        "  --output [file]              override destination path\n"
-        "  --output-h [file]            generate header file\n"
-        "  --output-lib [file]          override import library path\n"
+        "  --output-dir [dir]           override output directory (defaults to cwd)\n"
         "  --pkg-begin [name] [path]    make pkg available to import and push current pkg\n"
         "  --pkg-end                    pop current pkg\n"
         "  --main-pkg-path              set the directory of the root package\n"
@@ -371,8 +370,14 @@ int main(int argc, char **argv) {
                 fprintf(stderr, "Unable to make directory: %s: %s\n", buf_ptr(out_src_dir_path), err_str(err));
                 return EXIT_FAILURE;
             }
-            os_write_file(out_build_zig_path, modified_build_zig_contents);
-            os_write_file(out_main_zig_path, main_zig_contents);
+            if ((err = os_write_file(out_build_zig_path, modified_build_zig_contents))) {
+                fprintf(stderr, "Unable to write file: %s: %s\n", buf_ptr(out_build_zig_path), err_str(err));
+                return EXIT_FAILURE;
+            }
+            if ((err = os_write_file(out_main_zig_path, main_zig_contents))) {
+                fprintf(stderr, "Unable to write file: %s: %s\n", buf_ptr(out_main_zig_path), err_str(err));
+                return EXIT_FAILURE;
+            }
             fprintf(stderr, "Created %s\n", buf_ptr(out_build_zig_path));
             fprintf(stderr, "Created %s\n", buf_ptr(out_main_zig_path));
             if (init_kind == InitKindExe) {
@@ -390,9 +395,7 @@ int main(int argc, char **argv) {
     Cmd cmd = CmdNone;
     EmitFileType emit_file_type = EmitFileTypeBinary;
     const char *in_file = nullptr;
-    const char *out_file = nullptr;
-    const char *out_file_h = nullptr;
-    const char *out_file_lib = nullptr;
+    Buf *output_dir = nullptr;
     bool strip = false;
     bool is_static = false;
     OutType out_type = OutTypeUnknown;
@@ -406,7 +409,7 @@ int main(int argc, char **argv) {
     bool verbose_cc = false;
     ErrColor color = ErrColorAuto;
     CacheOpt enable_cache = CacheOptAuto;
-    const char *dynamic_linker = nullptr;
+    Buf *dynamic_linker = nullptr;
     const char *libc_txt = nullptr;
     ZigList<const char *> clang_argv = {0};
     ZigList<const char *> lib_dirs = {0};
@@ -438,6 +441,7 @@ int main(int argc, char **argv) {
     bool system_linker_hack = false;
     TargetSubsystem subsystem = TargetSubsystemAuto;
     bool is_single_threaded = false;
+    bool disable_gen_h = false;
     Buf *override_std_dir = nullptr;
     Buf *main_pkg_path = nullptr;
     ValgrindSupport valgrind_support = ValgrindSupportAuto;
@@ -648,6 +652,8 @@ int main(int argc, char **argv) {
                 system_linker_hack = true;
             } else if (strcmp(arg, "--single-threaded") == 0) {
                 is_single_threaded = true;
+            } else if (strcmp(arg, "--disable-gen-h") == 0) {
+                disable_gen_h = true;
             } else if (strcmp(arg, "--test-cmd-bin") == 0) {
                 test_exec_args.append(nullptr);
             } else if (arg[1] == 'L' && arg[2] != 0) {
@@ -677,12 +683,8 @@ int main(int argc, char **argv) {
                 return print_error_usage(arg0);
             } else {
                 i += 1;
-                if (strcmp(arg, "--output") == 0) {
-                    out_file = argv[i];
-                } else if (strcmp(arg, "--output-h") == 0) {
-                    out_file_h = argv[i];
-                } else if (strcmp(arg, "--output-lib") == 0) {
-                    out_file_lib = argv[i];
+                if (strcmp(arg, "--output-dir") == 0) {
+                    output_dir = buf_create_from_str(argv[i]);
                 } else if (strcmp(arg, "--color") == 0) {
                     if (strcmp(argv[i], "auto") == 0) {
                         color = ErrColorAuto;
@@ -719,7 +721,7 @@ int main(int argc, char **argv) {
                 } else if (strcmp(arg, "--name") == 0) {
                     out_name = argv[i];
                 } else if (strcmp(arg, "--dynamic-linker") == 0) {
-                    dynamic_linker = argv[i];
+                    dynamic_linker = buf_create_from_str(argv[i]);
                 } else if (strcmp(arg, "--libc") == 0) {
                     libc_txt = argv[i];
                 } else if (strcmp(arg, "-isystem") == 0) {
@@ -901,6 +903,21 @@ int main(int argc, char **argv) {
         }
     }
 
+    if (output_dir != nullptr && enable_cache == CacheOptOn) {
+        fprintf(stderr, "The --output-dir argument is incompatible with --cache on.\n");
+        return print_error_usage(arg0);
+    }
+
+    if (emit_file_type != EmitFileTypeBinary && in_file == nullptr) {
+        fprintf(stderr, "A root source file is required when using --emit asm or --emit llvm-ir");
+        return print_error_usage(arg0);
+    }
+
+    if (llvm_argv.length > 1) {
+        llvm_argv.append(nullptr);
+        ZigLLVMParseCommandLineOptions(llvm_argv.length - 1, llvm_argv.items);
+    }
+
     switch (cmd) {
     case CmdLibC: {
         if (in_file) {
@@ -1008,6 +1025,7 @@ int main(int argc, char **argv) {
             }
             CodeGen *g = codegen_create(main_pkg_path, zig_root_source_file, &target, out_type, build_mode,
                     get_zig_lib_dir(), override_std_dir, libc, cache_dir_buf);
+            if (llvm_argv.length >= 2) codegen_set_llvm_argv(g, llvm_argv.items + 1, llvm_argv.length - 2);
             g->valgrind_support = valgrind_support;
             g->subsystem = subsystem;
 
@@ -1030,16 +1048,9 @@ int main(int argc, char **argv) {
 
             codegen_set_clang_argv(g, clang_argv.items, clang_argv.length);
 
-            if (llvm_argv.length > 1) {
-                llvm_argv.append(nullptr);
-                ZigLLVMParseCommandLineOptions(llvm_argv.length - 1, llvm_argv.items);
-            }
-
-            codegen_set_llvm_argv(g, llvm_argv.items + 1, llvm_argv.length - 2);
             codegen_set_strip(g, strip);
             g->is_static = is_static;
-            if (dynamic_linker != nullptr)
-                codegen_set_dynamic_linker(g, buf_create_from_str(dynamic_linker));
+            g->dynamic_linker_path = dynamic_linker;
             g->verbose_tokenize = verbose_tokenize;
             g->verbose_ast = verbose_ast;
             g->verbose_link = verbose_link;
@@ -1047,6 +1058,8 @@ int main(int argc, char **argv) {
             g->verbose_llvm_ir = verbose_llvm_ir;
             g->verbose_cimport = verbose_cimport;
             g->verbose_cc = verbose_cc;
+            g->output_dir = output_dir;
+            g->disable_gen_h = disable_gen_h;
             codegen_set_errmsg_color(g, color);
             g->system_linker_hack = system_linker_hack;
 
@@ -1090,13 +1103,6 @@ int main(int argc, char **argv) {
                 codegen_set_test_name_prefix(g, buf_create_from_str(test_name_prefix));
             }
 
-            if (out_file)
-                codegen_set_output_path(g, buf_create_from_str(out_file));
-            if (out_file_h != nullptr && (out_type == OutTypeObj || out_type == OutTypeLib))
-                codegen_set_output_h_path(g, buf_create_from_str(out_file_h));
-            if (out_file_lib != nullptr && out_type == OutTypeLib && !is_static)
-                codegen_set_output_lib_path(g, buf_create_from_str(out_file_lib));
-
             add_package(g, cur_pkg, g->root_package);
 
             if (cmd == CmdBuild || cmd == CmdRun || cmd == CmdTest) {
@@ -1135,20 +1141,18 @@ int main(int argc, char **argv) {
                     return term.code;
                 } else if (cmd == CmdBuild) {
                     if (g->enable_cache) {
-                        printf("%s\n", buf_ptr(&g->output_file_path));
-                        if (g->out_h_path != nullptr) {
-                            printf("%s\n", buf_ptr(g->out_h_path));
-                        }
+                        if (printf("%s\n", buf_ptr(&g->output_file_path)) < 0)
+                            return EXIT_FAILURE;
                     }
                     return EXIT_SUCCESS;
                 } else {
                     zig_unreachable();
                 }
             } else if (cmd == CmdTranslateC) {
-                codegen_translate_c(g, in_file_buf);
-                ast_render(g, stdout, g->root_import->data.structure.decl_node, 4);
+                AstNode *root_node = codegen_translate_c(g, in_file_buf);
+                ast_render(g, stdout, root_node, 4);
                 if (timing_info)
-                    codegen_print_timing_report(g, stdout);
+                    codegen_print_timing_report(g, stderr);
                 return EXIT_SUCCESS;
             } else if (cmd == CmdTest) {
                 codegen_set_emit_file_type(g, emit_file_type);
@@ -1156,7 +1160,7 @@ int main(int argc, char **argv) {
                 ZigTarget native;
                 get_native_target(&native);
 
-                g->enable_cache = get_cache_opt(enable_cache, false);
+                g->enable_cache = get_cache_opt(enable_cache, true);
                 codegen_build_and_link(g);
 
                 if (timing_info) {
diff --git a/src/os.cpp b/src/os.cpp
index c50fb71884..d5195c92d8 100644
--- a/src/os.cpp
+++ b/src/os.cpp
@@ -1031,7 +1031,7 @@ Error os_exec_process(const char *exe, ZigList<const char *> &args,
 #endif
 }
 
-void os_write_file(Buf *full_path, Buf *contents) {
+Error os_write_file(Buf *full_path, Buf *contents) {
     FILE *f = fopen(buf_ptr(full_path), "wb");
     if (!f) {
         zig_panic("os_write_file failed for %s", buf_ptr(full_path));
@@ -1041,6 +1041,7 @@ void os_write_file(Buf *full_path, Buf *contents) {
         zig_panic("write failed: %s", strerror(errno));
     if (fclose(f))
         zig_panic("close failed");
+    return ErrorNone;
 }
 
 Error os_copy_file(Buf *src_path, Buf *dest_path) {
@@ -1208,91 +1209,6 @@ bool os_stderr_tty(void) {
 #endif
 }
 
-#if defined(ZIG_OS_POSIX)
-static Error os_buf_to_tmp_file_posix(Buf *contents, Buf *suffix, Buf *out_tmp_path) {
-    const char *tmp_dir = getenv("TMPDIR");
-    if (!tmp_dir) {
-        tmp_dir = P_tmpdir;
-    }
-    buf_resize(out_tmp_path, 0);
-    buf_appendf(out_tmp_path, "%s/XXXXXX%s", tmp_dir, buf_ptr(suffix));
-
-    int fd = mkstemps(buf_ptr(out_tmp_path), (int)buf_len(suffix));
-    if (fd < 0) {
-        return ErrorFileSystem;
-    }
-
-    FILE *f = fdopen(fd, "wb");
-    if (!f) {
-        zig_panic("fdopen failed");
-    }
-
-    size_t amt_written = fwrite(buf_ptr(contents), 1, buf_len(contents), f);
-    if (amt_written != (size_t)buf_len(contents))
-        zig_panic("write failed: %s", strerror(errno));
-    if (fclose(f))
-        zig_panic("close failed");
-
-    return ErrorNone;
-}
-#endif
-
-Buf *os_tmp_filename(Buf *prefix, Buf *suffix) {
-    Buf *result = buf_create_from_buf(prefix);
-
-    const char base64[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_";
-    assert(array_length(base64) == 64 + 1);
-    for (size_t i = 0; i < 12; i += 1) {
-        buf_append_char(result, base64[rand() % 64]);
-    }
-    buf_append_buf(result, suffix);
-    return result;
-}
-
-#if defined(ZIG_OS_WINDOWS)
-static Error os_buf_to_tmp_file_windows(Buf *contents, Buf *suffix, Buf *out_tmp_path) {
-    char tmp_dir[MAX_PATH + 1];
-    if (GetTempPath(MAX_PATH, tmp_dir) == 0) {
-        zig_panic("GetTempPath failed");
-    }
-    buf_init_from_str(out_tmp_path, tmp_dir);
-
-    const char base64[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_";
-    assert(array_length(base64) == 64 + 1);
-    for (size_t i = 0; i < 8; i += 1) {
-        buf_append_char(out_tmp_path, base64[rand() % 64]);
-    }
-
-    buf_append_buf(out_tmp_path, suffix);
-
-    FILE *f = fopen(buf_ptr(out_tmp_path), "wb");
-
-    if (!f) {
-        zig_panic("unable to open %s: %s", buf_ptr(out_tmp_path), strerror(errno));
-    }
-
-    size_t amt_written = fwrite(buf_ptr(contents), 1, buf_len(contents), f);
-    if (amt_written != (size_t)buf_len(contents)) {
-        zig_panic("write failed: %s", strerror(errno));
-    }
-
-    if (fclose(f)) {
-        zig_panic("fclose failed");
-    }
-    return ErrorNone;
-}
-#endif
-
-Error os_buf_to_tmp_file(Buf *contents, Buf *suffix, Buf *out_tmp_path) {
-#if defined(ZIG_OS_WINDOWS)
-    return os_buf_to_tmp_file_windows(contents, suffix, out_tmp_path);
-#elif defined(ZIG_OS_POSIX)
-    return os_buf_to_tmp_file_posix(contents, suffix, out_tmp_path);
-#else
-#error "missing os_buf_to_tmp_file implementation"
-#endif
-}
-
 Error os_delete_file(Buf *path) {
     if (remove(buf_ptr(path))) {
         return ErrorFileSystem;
diff --git a/src/os.hpp b/src/os.hpp
index 2e0b1ea88f..916158b4f3 100644
--- a/src/os.hpp
+++ b/src/os.hpp
@@ -110,8 +110,8 @@ Error ATTRIBUTE_MUST_USE os_file_read_all(OsFile file, Buf *contents);
 Error ATTRIBUTE_MUST_USE os_file_overwrite(OsFile file, Buf *contents);
 void os_file_close(OsFile file);
 
-void os_write_file(Buf *full_path, Buf *contents);
-Error os_copy_file(Buf *src_path, Buf *dest_path);
+Error ATTRIBUTE_MUST_USE os_write_file(Buf *full_path, Buf *contents);
+Error ATTRIBUTE_MUST_USE os_copy_file(Buf *src_path, Buf *dest_path);
 
 Error ATTRIBUTE_MUST_USE os_fetch_file(FILE *file, Buf *out_contents, bool skip_shebang);
 Error ATTRIBUTE_MUST_USE os_fetch_file_path(Buf *full_path, Buf *out_contents, bool skip_shebang);
@@ -121,8 +121,6 @@ Error ATTRIBUTE_MUST_USE os_get_cwd(Buf *out_cwd);
 bool os_stderr_tty(void);
 void os_stderr_set_color(TermColor color);
 
-Buf *os_tmp_filename(Buf *prefix, Buf *suffix);
-Error os_buf_to_tmp_file(Buf *contents, Buf *suffix, Buf *out_tmp_path);
 Error os_delete_file(Buf *path);
 
 Error ATTRIBUTE_MUST_USE os_file_exists(Buf *full_path, bool *result);
diff --git a/src/target.cpp b/src/target.cpp
index 5264184454..7eb4998f57 100644
--- a/src/target.cpp
+++ b/src/target.cpp
@@ -942,8 +942,12 @@ const char *target_lib_file_ext(const ZigTarget *target, bool is_static,
     } else {
         if (is_static) {
             return ".a";
+        } else if (target_is_darwin(target)) {
+            return buf_ptr(buf_sprintf(".%" ZIG_PRI_usize ".%" ZIG_PRI_usize ".%" ZIG_PRI_usize ".dylib",
+                        version_major, version_minor, version_patch));
         } else {
-            return buf_ptr(buf_sprintf(".so.%" ZIG_PRI_usize, version_major));
+            return buf_ptr(buf_sprintf(".so.%" ZIG_PRI_usize ".%" ZIG_PRI_usize ".%" ZIG_PRI_usize,
+                        version_major, version_minor, version_patch));
         }
     }
 }
diff --git a/src/translate_c.cpp b/src/translate_c.cpp
index bdedd78b35..c56d31eb2d 100644
--- a/src/translate_c.cpp
+++ b/src/translate_c.cpp
@@ -76,7 +76,6 @@ struct TransScopeWhile {
 };
 
 struct Context {
-    ZigType *import;
     ZigList<ErrorMsg *> *errors;
     VisibMod visib_mod;
     bool want_export;
@@ -86,7 +85,6 @@ struct Context {
     HashMap<Buf *, AstNode *, buf_hash, buf_eql_buf> global_table;
     ZigClangSourceManager *source_manager;
     ZigList<Alias> aliases;
-    AstNode *source_node;
     bool warnings_on;
 
     CodeGen *codegen;
@@ -190,7 +188,6 @@ static Buf *trans_lookup_zig_symbol(Context *c, TransScope *scope, Buf *c_symbol
 static AstNode * trans_create_node(Context *c, NodeType id) {
     AstNode *node = allocate<AstNode>(1);
     node->type = id;
-    node->owner = c->import;
     // TODO line/column. mapping to C file??
     return node;
 }
@@ -4732,29 +4729,12 @@ static void process_preprocessor_entities(Context *c, ZigClangASTUnit *zunit) {
     }
 }
 
-Error parse_h_buf(ZigType *import, ZigList<ErrorMsg *> *errors, Buf *source,
-        CodeGen *codegen, AstNode *source_node)
-{
-    Error err;
-    Buf tmp_file_path = BUF_INIT;
-    if ((err = os_buf_to_tmp_file(source, buf_create_from_str(".h"), &tmp_file_path))) {
-        return err;
-    }
-
-    err = parse_h_file(import, errors, buf_ptr(&tmp_file_path), codegen, source_node);
-
-    os_delete_file(&tmp_file_path);
-
-    return err;
-}
-
-Error parse_h_file(ZigType *import, ZigList<ErrorMsg *> *errors, const char *target_file,
-        CodeGen *codegen, AstNode *source_node)
+Error parse_h_file(AstNode **out_root_node, ZigList<ErrorMsg *> *errors, const char *target_file,
+        CodeGen *codegen, Buf *tmp_dep_file)
 {
     Context context = {0};
     Context *c = &context;
     c->warnings_on = codegen->verbose_cimport;
-    c->import = import;
     c->errors = errors;
     if (buf_ends_with_str(buf_create_from_str(target_file), ".h")) {
         c->visib_mod = VisibModPub;
@@ -4768,7 +4748,6 @@ Error parse_h_file(ZigType *import, ZigList<ErrorMsg *> *errors, const char *tar
     c->global_table.init(8);
     c->ptr_params.init(8);
     c->codegen = codegen;
-    c->source_node = source_node;
     c->global_scope = trans_scope_root_create(c);
 
     ZigList<const char *> clang_argv = {0};
@@ -4776,14 +4755,11 @@ Error parse_h_file(ZigType *import, ZigList<ErrorMsg *> *errors, const char *tar
     clang_argv.append("-x");
     clang_argv.append("c");
 
-    Buf *out_dep_path = nullptr;
-    if (codegen->enable_cache) {
-        Buf *prefix = buf_sprintf("%s" OS_SEP, buf_ptr(codegen->cache_dir));
-        out_dep_path = os_tmp_filename(prefix, buf_create_from_str(".d"));
+    if (tmp_dep_file != nullptr) {
         clang_argv.append("-MD");
         clang_argv.append("-MV");
         clang_argv.append("-MF");
-        clang_argv.append(buf_ptr(out_dep_path));
+        clang_argv.append(buf_ptr(tmp_dep_file));
     }
 
     if (c->codegen->zig_target->is_native) {
@@ -4847,7 +4823,7 @@ Error parse_h_file(ZigType *import, ZigList<ErrorMsg *> *errors, const char *tar
 
     clang_argv.append(target_file);
 
-    if (codegen->verbose_cimport) {
+    if (codegen->verbose_cc) {
         fprintf(stderr, "clang");
         for (size_t i = 0; i < clang_argv.length; i += 1) {
             fprintf(stderr, " %s", clang_argv.at(i));
@@ -4932,17 +4908,6 @@ Error parse_h_file(ZigType *import, ZigList<ErrorMsg *> *errors, const char *tar
         return ErrorCCompileErrors;
     }
 
-    if (codegen->enable_cache) {
-        Error err;
-        assert(out_dep_path != nullptr);
-        if ((err = cache_add_dep_file(&codegen->cache_hash, out_dep_path, codegen->verbose_cimport))) {
-            if (codegen->verbose_cimport) {
-                fprintf(stderr, "translate-c: aborting due to failed cache operation: %s\n", err_str(err));
-            }
-            return err;
-        }
-    }
-
     c->ctx = ZigClangASTUnit_getASTContext(ast_unit);
     c->source_manager = ZigClangASTUnit_getSourceManager(ast_unit);
     c->root = trans_create_node(c, NodeTypeContainerDecl);
@@ -4955,8 +4920,7 @@ Error parse_h_file(ZigType *import, ZigList<ErrorMsg *> *errors, const char *tar
     render_macros(c);
     render_aliases(c);
 
-    import->data.structure.decl_node = c->root;
-    import->data.structure.decls_scope->base.source_node = c->root;
+    *out_root_node = c->root;
 
     return ErrorNone;
 }
diff --git a/src/translate_c.hpp b/src/translate_c.hpp
index c4bd270c21..21461d2813 100644
--- a/src/translate_c.hpp
+++ b/src/translate_c.hpp
@@ -11,10 +11,7 @@
 
 #include "all_types.hpp"
 
-Error parse_h_file(ZigType *import, ZigList<ErrorMsg *> *errors, const char *target_file,
-        CodeGen *codegen, AstNode *source_node);
-
-Error parse_h_buf(ZigType *import, ZigList<ErrorMsg *> *errors, Buf *source,
-        CodeGen *codegen, AstNode *source_node);
+Error parse_h_file(AstNode **out_root_node, ZigList<ErrorMsg *> *errors, const char *target_file,
+        CodeGen *codegen, Buf *tmp_dep_file);
 
 #endif
diff --git a/std/build.zig b/std/build.zig
index 2316a87b31..8ff742d5a2 100644
--- a/std/build.zig
+++ b/std/build.zig
@@ -183,9 +183,20 @@ pub const Builder = struct {
         return obj_step;
     }
 
-    /// ::argv is copied.
-    pub fn addCommand(self: *Builder, cwd: ?[]const u8, env_map: *const BufMap, argv: []const []const u8) *CommandStep {
-        return CommandStep.create(self, cwd, env_map, argv);
+    /// Initializes a RunStep with argv, which must at least have the path to the
+    /// executable. More command line arguments can be added with `addArg`,
+    /// `addArgs`, and `addArtifactArg`.
+    /// Be careful using this function, as it introduces a system dependency.
+    /// To run an executable built with zig build, see `LibExeObjStep.run`.
+    pub fn addSystemCommand(self: *Builder, argv: []const []const u8) *RunStep {
+        assert(argv.len >= 1);
+        const run_step = RunStep.create(self, self.fmt("run {}", argv[0]));
+        run_step.addArgs(argv);
+        return run_step;
+    }
+
+    fn dupe(self: *Builder, bytes: []const u8) []u8 {
+        return mem.dupe(self.allocator, u8, bytes) catch unreachable;
     }
 
     pub fn addWriteFile(self: *Builder, file_path: []const u8, data: []const u8) *WriteFileStep {
@@ -702,25 +713,42 @@ pub const Builder = struct {
     }
 
     pub fn exec(self: *Builder, argv: []const []const u8) ![]u8 {
+        assert(argv.len != 0);
+
         const max_output_size = 100 * 1024;
-        const result = try os.ChildProcess.exec(self.allocator, argv, null, null, max_output_size);
-        switch (result.term) {
+        const child = try os.ChildProcess.init(argv, self.allocator);
+        defer child.deinit();
+
+        child.stdin_behavior = os.ChildProcess.StdIo.Ignore;
+        child.stdout_behavior = os.ChildProcess.StdIo.Pipe;
+        child.stderr_behavior = os.ChildProcess.StdIo.Inherit;
+
+        try child.spawn();
+
+        var stdout = std.Buffer.initNull(self.allocator);
+        defer std.Buffer.deinit(&stdout);
+
+        var stdout_file_in_stream = child.stdout.?.inStream();
+        try stdout_file_in_stream.stream.readAllBuffer(&stdout, max_output_size);
+
+        const term = child.wait() catch |err| std.debug.panic("unable to spawn {}: {}", argv[0], err);
+        switch (term) {
             os.ChildProcess.Term.Exited => |code| {
                 if (code != 0) {
                     warn("The following command exited with error code {}:\n", code);
                     printCmd(null, argv);
-                    warn("stderr:{}\n", result.stderr);
-                    std.debug.panic("command failed");
+                    std.debug.panic("exec failed");
                 }
-                return result.stdout;
+                return stdout.toOwnedSlice();
             },
             else => {
                 warn("The following command terminated unexpectedly:\n");
                 printCmd(null, argv);
-                warn("stderr:{}\n", result.stderr);
-                std.debug.panic("command failed");
+                std.debug.panic("exec failed");
             },
         }
+
+        return stdout.toOwnedSlice();
     }
 
     pub fn addSearchPrefix(self: *Builder, search_prefix: []const u8) void {
@@ -837,26 +865,20 @@ pub const LibExeObjStep = struct {
     builder: *Builder,
     name: []const u8,
     target: Target,
-    link_libs: BufSet,
     linker_script: ?[]const u8,
     out_filename: []const u8,
-    output_path: ?[]const u8,
-    output_lib_path: ?[]const u8,
     static: bool,
     version: Version,
-    object_files: ArrayList([]const u8),
     build_mode: builtin.Mode,
     kind: Kind,
     major_only_filename: []const u8,
     name_only_filename: []const u8,
     strip: bool,
-    full_path_libs: ArrayList([]const u8),
-    need_flat_namespace_hack: bool,
-    include_dirs: ArrayList([]const u8),
     lib_paths: ArrayList([]const u8),
     frameworks: BufSet,
     verbose_link: bool,
     verbose_cc: bool,
+    disable_gen_h: bool,
     c_std: Builder.CStd,
     override_std_dir: ?[]const u8,
     main_pkg_path: ?[]const u8,
@@ -865,17 +887,31 @@ pub const LibExeObjStep = struct {
     filter: ?[]const u8,
 
     root_src: ?[]const u8,
-    output_h_path: ?[]const u8,
     out_h_filename: []const u8,
     out_lib_filename: []const u8,
-    assembly_files: ArrayList([]const u8),
     packages: ArrayList(Pkg),
     build_options_contents: std.Buffer,
     system_linker_hack: bool,
 
-    c_source_files: ArrayList(*CSourceFile),
     object_src: []const u8,
 
+    link_objects: ArrayList(LinkObject),
+    include_dirs: ArrayList(IncludeDir),
+    output_dir: ?[]const u8,
+
+    const LinkObject = union(enum) {
+        StaticPath: []const u8,
+        OtherStep: *LibExeObjStep,
+        SystemLib: []const u8,
+        AssemblyFile: []const u8,
+        CSourceFile: *CSourceFile,
+    };
+
+    const IncludeDir = union(enum) {
+        RawPath: []const u8,
+        OtherStep: *LibExeObjStep,
+    };
+
     const Kind = enum {
         Exe,
         Lib,
@@ -926,25 +962,17 @@ pub const LibExeObjStep = struct {
             .name = name,
             .target = Target.Native,
             .linker_script = null,
-            .link_libs = BufSet.init(builder.allocator),
             .frameworks = BufSet.init(builder.allocator),
             .step = Step.init(name, builder.allocator, make),
-            .output_path = null,
-            .output_lib_path = null,
-            .output_h_path = null,
             .version = ver,
             .out_filename = undefined,
             .out_h_filename = builder.fmt("{}.h", name),
             .out_lib_filename = undefined,
             .major_only_filename = undefined,
             .name_only_filename = undefined,
-            .object_files = ArrayList([]const u8).init(builder.allocator),
-            .assembly_files = ArrayList([]const u8).init(builder.allocator),
             .packages = ArrayList(Pkg).init(builder.allocator),
-            .full_path_libs = ArrayList([]const u8).init(builder.allocator),
-            .need_flat_namespace_hack = false,
-            .c_source_files = ArrayList(*CSourceFile).init(builder.allocator),
-            .include_dirs = ArrayList([]const u8).init(builder.allocator),
+            .include_dirs = ArrayList(IncludeDir).init(builder.allocator),
+            .link_objects = ArrayList(LinkObject).init(builder.allocator),
             .lib_paths = ArrayList([]const u8).init(builder.allocator),
             .object_src = undefined,
             .build_options_contents = std.Buffer.initSize(builder.allocator, 0) catch unreachable,
@@ -955,6 +983,8 @@ pub const LibExeObjStep = struct {
             .exec_cmd_args = null,
             .name_prefix = "",
             .filter = null,
+            .disable_gen_h = false,
+            .output_dir = null,
         };
         self.computeOutFileNames();
         return self;
@@ -1022,7 +1052,19 @@ pub const LibExeObjStep = struct {
         self.computeOutFileNames();
     }
 
-    // TODO respect this in the C args
+    pub fn setOutputDir(self: *LibExeObjStep, dir: []const u8) void {
+        self.output_dir = self.builder.dupe(dir);
+    }
+
+    /// Creates a `RunStep` with an executable built with `addExecutable`.
+    /// Add command line arguments with `addArg`.
+    pub fn run(exe: *LibExeObjStep) *RunStep {
+        assert(exe.kind == Kind.Exe);
+        const run_step = RunStep.create(exe.builder, exe.builder.fmt("run {}", exe.step.name));
+        run_step.addArtifactArg(exe);
+        return run_step;
+    }
+
     pub fn setLinkerScriptPath(self: *LibExeObjStep, path: []const u8) void {
         self.linker_script = path;
     }
@@ -1032,37 +1074,28 @@ pub const LibExeObjStep = struct {
         self.frameworks.put(framework_name) catch unreachable;
     }
 
-    pub fn linkLibrary(self: *LibExeObjStep, lib: *LibExeObjStep) void {
-        assert(self.kind != Kind.Obj);
-        assert(lib.kind == Kind.Lib);
-
-        self.step.dependOn(&lib.step);
-
-        if (lib.static or self.target.isWindows()) {
-            self.object_files.append(lib.getOutputLibPath()) catch unreachable;
-        } else {
-            self.full_path_libs.append(lib.getOutputPath()) catch unreachable;
-        }
-
-        if (lib.link_libs.exists("c")) {
-            self.link_libs.put("c") catch unreachable;
-        }
-
-        // TODO should be some kind of isolated directory that only has this header in it
-        self.include_dirs.append(self.builder.cache_root) catch unreachable;
-        self.need_flat_namespace_hack = true;
-
-        // inherit the object's frameworks
-        if (self.target.isDarwin() and lib.static) {
-            var it = lib.frameworks.iterator();
-            while (it.next()) |entry| {
-                self.frameworks.put(entry.key) catch unreachable;
+    /// Returns whether the library, executable, or object depends on a particular system library.
+    pub fn dependsOnSystemLibrary(self: LibExeObjStep, name: []const u8) bool {
+        for (self.link_objects.toSliceConst()) |link_object| {
+            switch (link_object) {
+                LinkObject.SystemLib => |n| if (mem.eql(u8, n, name)) return true,
+                else => continue,
             }
         }
+        return false;
+    }
+
+    pub fn linkLibrary(self: *LibExeObjStep, lib: *LibExeObjStep) void {
+        assert(lib.kind == Kind.Lib);
+        self.linkLibraryOrObject(lib);
+    }
+
+    pub fn isDynamicLibrary(self: *LibExeObjStep) bool {
+        return self.kind == Kind.Lib and !self.static;
     }
 
     pub fn linkSystemLibrary(self: *LibExeObjStep, name: []const u8) void {
-        self.link_libs.put(name) catch unreachable;
+        self.link_objects.append(LinkObject{ .SystemLib = self.builder.dupe(name) }) catch unreachable;
     }
 
     pub fn setNamePrefix(self: *LibExeObjStep, text: []const u8) void {
@@ -1077,11 +1110,15 @@ pub const LibExeObjStep = struct {
 
     pub fn addCSourceFile(self: *LibExeObjStep, file: []const u8, args: []const []const u8) void {
         const c_source_file = self.builder.allocator.create(CSourceFile) catch unreachable;
+        const args_copy = self.builder.allocator.alloc([]u8, args.len) catch unreachable;
+        for (args) |arg, i| {
+            args_copy[i] = self.builder.dupe(arg);
+        }
         c_source_file.* = CSourceFile{
-            .source_path = file,
-            .args = args,
+            .source_path = self.builder.dupe(file),
+            .args = args_copy,
         };
-        self.c_source_files.append(c_source_file) catch unreachable;
+        self.link_objects.append(LinkObject{ .CSourceFile = c_source_file }) catch unreachable;
     }
 
     pub fn setVerboseLink(self: *LibExeObjStep, value: bool) void {
@@ -1104,78 +1141,48 @@ pub const LibExeObjStep = struct {
         self.main_pkg_path = dir_path;
     }
 
-    pub fn setOutputPath(self: *LibExeObjStep, file_path: []const u8) void {
-        self.output_path = file_path;
-
-        // catch a common mistake
-        if (mem.eql(u8, self.builder.pathFromRoot(file_path), self.builder.pathFromRoot("."))) {
-            debug.panic("setOutputPath wants a file path, not a directory\n");
-        }
-    }
-
+    /// Unless setOutputDir was called, this function must be called only in
+    /// the make step, from a step that has declared a dependency on this one.
+    /// To run an executable built with zig build, use `run`, or create an install step and invoke it.
     pub fn getOutputPath(self: *LibExeObjStep) []const u8 {
-        return if (self.output_path) |output_path| output_path else os.path.join(
+        return os.path.join(
             self.builder.allocator,
-            [][]const u8{ self.builder.cache_root, self.out_filename },
+            [][]const u8{ self.output_dir.?, self.out_filename },
         ) catch unreachable;
     }
 
-    pub fn setOutputLibPath(self: *LibExeObjStep, file_path: []const u8) void {
-        assert(self.kind == Kind.Lib);
-        if (self.static)
-            return self.setOutputPath(file_path);
-
-        self.output_lib_path = file_path;
-    }
-
+    /// Unless setOutputDir was called, this function must be called only in
+    /// the make step, from a step that has declared a dependency on this one.
     pub fn getOutputLibPath(self: *LibExeObjStep) []const u8 {
         assert(self.kind == Kind.Lib);
-        return if (self.output_lib_path) |output_lib_path| output_lib_path else os.path.join(
+        return os.path.join(
             self.builder.allocator,
-            [][]const u8{ self.builder.cache_root, self.out_lib_filename },
+            [][]const u8{ self.output_dir.?, self.out_lib_filename },
         ) catch unreachable;
     }
 
-    pub fn setOutputHPath(self: *LibExeObjStep, file_path: []const u8) void {
-        self.output_h_path = file_path;
-
-        // catch a common mistake
-        if (mem.eql(u8, self.builder.pathFromRoot(file_path), self.builder.pathFromRoot("."))) {
-            debug.panic("setOutputHPath wants a file path, not a directory\n");
-        }
-    }
-
+    /// Unless setOutputDir was called, this function must be called only in
+    /// the make step, from a step that has declared a dependency on this one.
     pub fn getOutputHPath(self: *LibExeObjStep) []const u8 {
-        return if (self.output_h_path) |output_h_path| output_h_path else os.path.join(
+        assert(self.kind != Kind.Exe);
+        assert(!self.disable_gen_h);
+        return os.path.join(
             self.builder.allocator,
-            [][]const u8{ self.builder.cache_root, self.out_h_filename },
+            [][]const u8{ self.output_dir.?, self.out_h_filename },
         ) catch unreachable;
     }
 
     pub fn addAssemblyFile(self: *LibExeObjStep, path: []const u8) void {
-        self.assembly_files.append(path) catch unreachable;
+        self.link_objects.append(LinkObject{ .AssemblyFile = self.builder.dupe(path) }) catch unreachable;
     }
 
     pub fn addObjectFile(self: *LibExeObjStep, path: []const u8) void {
-        assert(self.kind != Kind.Obj);
-
-        self.object_files.append(path) catch unreachable;
+        self.link_objects.append(LinkObject{ .StaticPath = self.builder.dupe(path) }) catch unreachable;
     }
 
     pub fn addObject(self: *LibExeObjStep, obj: *LibExeObjStep) void {
         assert(obj.kind == Kind.Obj);
-        assert(self.kind != Kind.Obj);
-
-        self.step.dependOn(&obj.step);
-
-        self.object_files.append(obj.getOutputPath()) catch unreachable;
-
-        // TODO should be some kind of isolated directory that only has this header in it
-        self.include_dirs.append(self.builder.cache_root) catch unreachable;
-
-        if (obj.link_libs.exists("c")) {
-            self.link_libs.put("c") catch unreachable;
-        }
+        self.linkLibraryOrObject(obj);
     }
 
     pub fn addBuildOption(self: *LibExeObjStep, comptime T: type, name: []const u8, value: T) void {
@@ -1184,7 +1191,7 @@ pub const LibExeObjStep = struct {
     }
 
     pub fn addIncludeDir(self: *LibExeObjStep, path: []const u8) void {
-        self.include_dirs.append(path) catch unreachable;
+        self.include_dirs.append(IncludeDir{ .RawPath = self.builder.dupe(path) }) catch unreachable;
     }
 
     pub fn addLibPath(self: *LibExeObjStep, path: []const u8) void {
@@ -1207,13 +1214,30 @@ pub const LibExeObjStep = struct {
         self.system_linker_hack = true;
     }
 
+    fn linkLibraryOrObject(self: *LibExeObjStep, other: *LibExeObjStep) void {
+        self.step.dependOn(&other.step);
+        self.link_objects.append(LinkObject{ .OtherStep = other }) catch unreachable;
+        self.include_dirs.append(IncludeDir{ .OtherStep = other }) catch unreachable;
+
+        // Inherit dependency on libc
+        if (other.dependsOnSystemLibrary("c")) {
+            self.linkSystemLibrary("c");
+        }
+
+        // Inherit dependencies on darwin frameworks
+        if (self.target.isDarwin() and !other.isDynamicLibrary()) {
+            var it = other.frameworks.iterator();
+            while (it.next()) |entry| {
+                self.frameworks.put(entry.key) catch unreachable;
+            }
+        }
+    }
+
     fn make(step: *Step) !void {
         const self = @fieldParentPtr(LibExeObjStep, "step", step);
         const builder = self.builder;
 
-        if (self.root_src == null and self.object_files.len == 0 and
-            self.assembly_files.len == 0 and self.c_source_files.len == 0)
-        {
+        if (self.root_src == null and self.link_objects.len == 0) {
             warn("{}: linker needs 1 or more objects to link\n", self.step.name);
             return error.NeedAnObject;
         }
@@ -1235,12 +1259,52 @@ pub const LibExeObjStep = struct {
             zig_args.append(builder.pathFromRoot(root_src)) catch unreachable;
         }
 
-        for (self.c_source_files.toSliceConst()) |c_source_file| {
-            try zig_args.append("--c-source");
-            for (c_source_file.args) |arg| {
-                try zig_args.append(arg);
+        for (self.link_objects.toSlice()) |link_object| {
+            switch (link_object) {
+                LinkObject.StaticPath => |static_path| {
+                    try zig_args.append("--object");
+                    try zig_args.append(builder.pathFromRoot(static_path));
+                },
+
+                LinkObject.OtherStep => |other| switch (other.kind) {
+                    LibExeObjStep.Kind.Exe => unreachable,
+                    LibExeObjStep.Kind.Test => unreachable,
+                    LibExeObjStep.Kind.Obj => {
+                        try zig_args.append("--object");
+                        try zig_args.append(other.getOutputPath());
+                    },
+                    LibExeObjStep.Kind.Lib => {
+                        if (other.static or self.target.isWindows()) {
+                            try zig_args.append("--object");
+                            try zig_args.append(other.getOutputPath());
+                        } else {
+                            const full_path_lib = other.getOutputPath();
+                            try zig_args.append("--library");
+                            try zig_args.append(full_path_lib);
+
+                            if (os.path.dirname(full_path_lib)) |dirname| {
+                                try zig_args.append("-rpath");
+                                try zig_args.append(dirname);
+                            }
+                        }
+                    },
+                },
+                LinkObject.SystemLib => |name| {
+                    try zig_args.append("--library");
+                    try zig_args.append(name);
+                },
+                LinkObject.AssemblyFile => |asm_file| {
+                    try zig_args.append("--assembly");
+                    try zig_args.append(builder.pathFromRoot(asm_file));
+                },
+                LinkObject.CSourceFile => |c_source_file| {
+                    try zig_args.append("--c-source");
+                    for (c_source_file.args) |arg| {
+                        try zig_args.append(arg);
+                    }
+                    try zig_args.append(self.builder.pathFromRoot(c_source_file.source_path));
+                },
             }
-            try zig_args.append(self.builder.pathFromRoot(c_source_file.source_path));
         }
 
         if (self.build_options_contents.len() > 0) {
@@ -1265,16 +1329,6 @@ pub const LibExeObjStep = struct {
             try zig_args.append(self.name_prefix);
         }
 
-        for (self.object_files.toSliceConst()) |object_file| {
-            zig_args.append("--object") catch unreachable;
-            zig_args.append(builder.pathFromRoot(object_file)) catch unreachable;
-        }
-
-        for (self.assembly_files.toSliceConst()) |asm_file| {
-            zig_args.append("--assembly") catch unreachable;
-            zig_args.append(builder.pathFromRoot(asm_file)) catch unreachable;
-        }
-
         if (builder.verbose_tokenize) zig_args.append("--verbose-tokenize") catch unreachable;
         if (builder.verbose_ast) zig_args.append("--verbose-ast") catch unreachable;
         if (builder.verbose_cimport) zig_args.append("--verbose-cimport") catch unreachable;
@@ -1294,24 +1348,8 @@ pub const LibExeObjStep = struct {
             builtin.Mode.ReleaseSmall => zig_args.append("--release-small") catch unreachable,
         }
 
-        zig_args.append("--cache-dir") catch unreachable;
-        zig_args.append(builder.pathFromRoot(builder.cache_root)) catch unreachable;
-
-        const output_path = builder.pathFromRoot(self.getOutputPath());
-        zig_args.append("--output") catch unreachable;
-        zig_args.append(output_path) catch unreachable;
-
-        if (self.kind == Kind.Lib and !self.static) {
-            const output_lib_path = builder.pathFromRoot(self.getOutputLibPath());
-            zig_args.append("--output-lib") catch unreachable;
-            zig_args.append(output_lib_path) catch unreachable;
-        }
-
-        if (self.kind != Kind.Exe and self.root_src != null) {
-            const output_h_path = self.getOutputHPath();
-            zig_args.append("--output-h") catch unreachable;
-            zig_args.append(builder.pathFromRoot(output_h_path)) catch unreachable;
-        }
+        try zig_args.append("--cache-dir");
+        try zig_args.append(builder.pathFromRoot(builder.cache_root));
 
         zig_args.append("--name") catch unreachable;
         zig_args.append(self.name) catch unreachable;
@@ -1351,15 +1389,6 @@ pub const LibExeObjStep = struct {
             zig_args.append(linker_script) catch unreachable;
         }
 
-        {
-            var it = self.link_libs.iterator();
-            while (true) {
-                const entry = it.next() orelse break;
-                zig_args.append("--library") catch unreachable;
-                zig_args.append(entry.key) catch unreachable;
-            }
-        }
-
         if (self.exec_cmd_args) |exec_cmd_args| {
             for (exec_cmd_args) |cmd_arg| {
                 if (cmd_arg) |arg| {
@@ -1377,9 +1406,18 @@ pub const LibExeObjStep = struct {
             zig_args.append("--pkg-end") catch unreachable;
         }
 
-        for (self.include_dirs.toSliceConst()) |include_path| {
-            zig_args.append("-isystem") catch unreachable;
-            zig_args.append(self.builder.pathFromRoot(include_path)) catch unreachable;
+        for (self.include_dirs.toSliceConst()) |include_dir| {
+            switch (include_dir) {
+                IncludeDir.RawPath => |include_path| {
+                    try zig_args.append("-isystem");
+                    try zig_args.append(self.builder.pathFromRoot(include_path));
+                },
+                IncludeDir.OtherStep => |other| {
+                    const h_path = other.getOutputHPath();
+                    try zig_args.append("-isystem");
+                    try zig_args.append(os.path.dirname(h_path).?);
+                },
+            }
         }
 
         for (builder.include_paths.toSliceConst()) |include_path| {
@@ -1402,17 +1440,6 @@ pub const LibExeObjStep = struct {
             zig_args.append(lib_path) catch unreachable;
         }
 
-        for (self.full_path_libs.toSliceConst()) |full_path_lib| {
-            try zig_args.append("--library");
-            try zig_args.append(builder.pathFromRoot(full_path_lib));
-
-            const full_path_lib_abs = builder.pathFromRoot(full_path_lib);
-            if (os.path.dirname(full_path_lib_abs)) |dirname| {
-                try zig_args.append("-rpath");
-                try zig_args.append(dirname);
-            }
-        }
-
         if (self.target.isDarwin()) {
             var it = self.frameworks.iterator();
             while (it.next()) |entry| {
@@ -1435,42 +1462,96 @@ pub const LibExeObjStep = struct {
             try zig_args.append(builder.pathFromRoot(dir));
         }
 
-        try builder.spawnChild(zig_args.toSliceConst());
+        if (self.output_dir) |output_dir| {
+            try zig_args.append("--output-dir");
+            try zig_args.append(output_dir);
+
+            try builder.spawnChild(zig_args.toSliceConst());
+        } else if (self.kind == Kind.Test) {
+            try builder.spawnChild(zig_args.toSliceConst());
+        } else {
+            try zig_args.append("--cache");
+            try zig_args.append("on");
+
+            const output_path_nl = try builder.exec(zig_args.toSliceConst());
+            const output_path = mem.trimRight(u8, output_path_nl, "\r\n");
+            self.output_dir = os.path.dirname(output_path).?;
+        }
 
         if (self.kind == Kind.Lib and !self.static and self.target.wantSharedLibSymLinks()) {
-            try doAtomicSymLinks(builder.allocator, output_path, self.major_only_filename, self.name_only_filename);
+            try doAtomicSymLinks(builder.allocator, self.getOutputPath(), self.major_only_filename, self.name_only_filename);
         }
     }
 };
 
-pub const CommandStep = struct {
+pub const RunStep = struct {
     step: Step,
     builder: *Builder,
-    argv: [][]const u8,
+
+    /// See also addArg and addArgs to modifying this directly
+    argv: ArrayList(Arg),
+
+    /// Set this to modify the current working directory
     cwd: ?[]const u8,
-    env_map: *const BufMap,
 
-    /// ::argv is copied.
-    pub fn create(builder: *Builder, cwd: ?[]const u8, env_map: *const BufMap, argv: []const []const u8) *CommandStep {
-        const self = builder.allocator.create(CommandStep) catch unreachable;
-        self.* = CommandStep{
+    /// Override this field to modify the environment, or use setEnvironmentVariable
+    env_map: ?*const BufMap,
+
+    pub const Arg = union(enum) {
+        Artifact: *LibExeObjStep,
+        Bytes: []u8,
+    };
+
+    pub fn create(builder: *Builder, name: []const u8) *RunStep {
+        const self = builder.allocator.create(RunStep) catch unreachable;
+        self.* = RunStep{
             .builder = builder,
-            .step = Step.init(argv[0], builder.allocator, make),
-            .argv = builder.allocator.alloc([]u8, argv.len) catch unreachable,
-            .cwd = cwd,
-            .env_map = env_map,
+            .step = Step.init(name, builder.allocator, make),
+            .argv = ArrayList(Arg).init(builder.allocator),
+            .cwd = null,
+            .env_map = null,
         };
-
-        mem.copy([]const u8, self.argv, argv);
-        self.step.name = self.argv[0];
         return self;
     }
 
+    pub fn addArtifactArg(self: *RunStep, artifact: *LibExeObjStep) void {
+        self.argv.append(Arg{ .Artifact = artifact }) catch unreachable;
+        self.step.dependOn(&artifact.step);
+    }
+
+    pub fn addArg(self: *RunStep, arg: []const u8) void {
+        self.argv.append(Arg{ .Bytes = self.builder.dupe(arg) }) catch unreachable;
+    }
+
+    pub fn addArgs(self: *RunStep, args: []const []const u8) void {
+        for (args) |arg| {
+            self.addArg(arg);
+        }
+    }
+
+    pub fn setEnvironmentVariable(self: *RunStep, key: []const u8, value: []const u8) void {
+        const env_map = self.env_map orelse blk: {
+            const env_map = os.getEnvMap(allocator) catch unreachable;
+            self.env_map = env_map;
+            break :blk env_map;
+        };
+        env_map.set(key, value) catch unreachable;
+    }
+
     fn make(step: *Step) !void {
-        const self = @fieldParentPtr(CommandStep, "step", step);
+        const self = @fieldParentPtr(RunStep, "step", step);
 
         const cwd = if (self.cwd) |cwd| self.builder.pathFromRoot(cwd) else self.builder.build_root;
-        return self.builder.spawnChildEnvMap(cwd, self.env_map, self.argv);
+
+        var argv = ArrayList([]const u8).init(self.builder.allocator);
+        for (self.argv.toSlice()) |arg| {
+            switch (arg) {
+                Arg.Bytes => |bytes| try argv.append(bytes),
+                Arg.Artifact => |artifact| try argv.append(artifact.getOutputPath()),
+            }
+        }
+
+        return self.builder.spawnChildEnvMap(cwd, self.env_map orelse self.builder.env_map, argv.toSliceConst());
     }
 };
 
diff --git a/std/special/init-exe/build.zig b/std/special/init-exe/build.zig
index 21a2600562..1ee3289643 100644
--- a/std/special/init-exe/build.zig
+++ b/std/special/init-exe/build.zig
@@ -5,10 +5,10 @@ pub fn build(b: *Builder) void {
     const exe = b.addExecutable("$", "src/main.zig");
     exe.setBuildMode(mode);
 
+    const run_cmd = exe.run();
+
     const run_step = b.step("run", "Run the app");
-    const run_cmd = b.addCommand(".", b.env_map, [][]const u8{exe.getOutputPath()});
     run_step.dependOn(&run_cmd.step);
-    run_cmd.step.dependOn(&exe.step);
 
     b.default_step.dependOn(&exe.step);
     b.installArtifact(exe);
diff --git a/test/cli.zig b/test/cli.zig
index 1520b3bde0..a36c810cd8 100644
--- a/test/cli.zig
+++ b/test/cli.zig
@@ -116,12 +116,12 @@ fn testGodboltApi(zig_exe: []const u8, dir_path: []const u8) anyerror!void {
     const args = [][]const u8{
         zig_exe, "build-obj",
         "--cache-dir", dir_path,
-        "--output", example_s_path,
-        "--output-h", "/dev/null",
+        "--name", "example",
+        "--output-dir", dir_path,
         "--emit", "asm",
         "-mllvm", "--x86-asm-syntax=intel",
         "--strip", "--release-fast",
-        example_zig_path,
+        example_zig_path, "--disable-gen-h",
     };
     _ = try exec(dir_path, args);
 
diff --git a/test/standalone/load_dynamic_library/build.zig b/test/standalone/load_dynamic_library/build.zig
index 2d47a893f2..109c742c6f 100644
--- a/test/standalone/load_dynamic_library/build.zig
+++ b/test/standalone/load_dynamic_library/build.zig
@@ -9,12 +9,8 @@ pub fn build(b: *Builder) void {
     const main = b.addExecutable("main", "main.zig");
     main.setBuildMode(opts);
 
-    const run = b.addCommand(".", b.env_map, [][]const u8{
-        main.getOutputPath(),
-        lib.getOutputPath(),
-    });
-    run.step.dependOn(&lib.step);
-    run.step.dependOn(&main.step);
+    const run = main.run();
+    run.addArtifactArg(lib);
 
     const test_step = b.step("test", "Test the program");
     test_step.dependOn(&run.step);
diff --git a/test/standalone/pkg_import/build.zig b/test/standalone/pkg_import/build.zig
index e0b3885dc3..7529d106f9 100644
--- a/test/standalone/pkg_import/build.zig
+++ b/test/standalone/pkg_import/build.zig
@@ -9,8 +9,7 @@ pub fn build(b: *Builder) void {
     exe.setBuildMode(b.standardReleaseOptions());
     exe.setBuildMode(b.standardReleaseOptions());
 
-    const run = b.addCommand(".", b.env_map, [][]const u8{exe.getOutputPath()});
-    run.step.dependOn(&exe.step);
+    const run = exe.run();
 
     const test_step = b.step("test", "Test it");
     test_step.dependOn(&run.step);
diff --git a/test/tests.zig b/test/tests.zig
index d3a27f3e94..ba713902ba 100644
--- a/test/tests.zig
+++ b/test/tests.zig
@@ -12,6 +12,7 @@ const fmt = std.fmt;
 const ArrayList = std.ArrayList;
 const builtin = @import("builtin");
 const Mode = builtin.Mode;
+const LibExeObjStep = build.LibExeObjStep;
 
 const compare_output = @import("compare_output.zig");
 const build_examples = @import("build_examples.zig");
@@ -111,12 +112,11 @@ pub fn addCliTests(b: *build.Builder, test_filter: ?[]const u8, modes: []const M
     const step = b.step("test-cli", "Test the command line interface");
 
     const exe = b.addExecutable("test-cli", "test/cli.zig");
-    const run_cmd = b.addCommand(null, b.env_map, [][]const u8{
-        b.pathFromRoot(exe.getOutputPath()),
+    const run_cmd = exe.run();
+    run_cmd.addArgs([][]const u8{
         os.path.realAlloc(b.allocator, b.zig_exe) catch unreachable,
         b.pathFromRoot(b.cache_root),
     });
-    run_cmd.step.dependOn(&exe.step);
 
     step.dependOn(&run_cmd.step);
     return step;
@@ -246,24 +246,31 @@ pub const CompareOutputContext = struct {
     const RunCompareOutputStep = struct {
         step: build.Step,
         context: *CompareOutputContext,
-        exe_path: []const u8,
+        exe: *LibExeObjStep,
         name: []const u8,
         expected_output: []const u8,
         test_index: usize,
         cli_args: []const []const u8,
 
-        pub fn create(context: *CompareOutputContext, exe_path: []const u8, name: []const u8, expected_output: []const u8, cli_args: []const []const u8) *RunCompareOutputStep {
+        pub fn create(
+            context: *CompareOutputContext,
+            exe: *LibExeObjStep,
+            name: []const u8,
+            expected_output: []const u8,
+            cli_args: []const []const u8,
+        ) *RunCompareOutputStep {
             const allocator = context.b.allocator;
             const ptr = allocator.create(RunCompareOutputStep) catch unreachable;
             ptr.* = RunCompareOutputStep{
                 .context = context,
-                .exe_path = exe_path,
+                .exe = exe,
                 .name = name,
                 .expected_output = expected_output,
                 .test_index = context.test_index,
                 .step = build.Step.init("RunCompareOutput", allocator, make),
                 .cli_args = cli_args,
             };
+            ptr.step.dependOn(&exe.step);
             context.test_index += 1;
             return ptr;
         }
@@ -272,7 +279,7 @@ pub const CompareOutputContext = struct {
             const self = @fieldParentPtr(RunCompareOutputStep, "step", step);
             const b = self.context.b;
 
-            const full_exe_path = b.pathFromRoot(self.exe_path);
+            const full_exe_path = self.exe.getOutputPath();
             var args = ArrayList([]const u8).init(b.allocator);
             defer args.deinit();
 
@@ -336,21 +343,21 @@ pub const CompareOutputContext = struct {
     const RuntimeSafetyRunStep = struct {
         step: build.Step,
         context: *CompareOutputContext,
-        exe_path: []const u8,
+        exe: *LibExeObjStep,
         name: []const u8,
         test_index: usize,
 
-        pub fn create(context: *CompareOutputContext, exe_path: []const u8, name: []const u8) *RuntimeSafetyRunStep {
+        pub fn create(context: *CompareOutputContext, exe: *LibExeObjStep, name: []const u8) *RuntimeSafetyRunStep {
             const allocator = context.b.allocator;
             const ptr = allocator.create(RuntimeSafetyRunStep) catch unreachable;
             ptr.* = RuntimeSafetyRunStep{
                 .context = context,
-                .exe_path = exe_path,
+                .exe = exe,
                 .name = name,
                 .test_index = context.test_index,
                 .step = build.Step.init("RuntimeSafetyRun", allocator, make),
             };
-
+            ptr.step.dependOn(&exe.step);
             context.test_index += 1;
             return ptr;
         }
@@ -359,11 +366,11 @@ pub const CompareOutputContext = struct {
             const self = @fieldParentPtr(RuntimeSafetyRunStep, "step", step);
             const b = self.context.b;
 
-            const full_exe_path = b.pathFromRoot(self.exe_path);
+            const full_exe_path = self.exe.getOutputPath();
 
             warn("Test {}/{} {}...", self.test_index + 1, self.context.test_index, self.name);
 
-            const child = os.ChildProcess.init([][]u8{full_exe_path}, b.allocator) catch unreachable;
+            const child = os.ChildProcess.init([][]const u8{full_exe_path}, b.allocator) catch unreachable;
             defer child.deinit();
 
             child.env_map = b.env_map;
@@ -463,8 +470,13 @@ pub const CompareOutputContext = struct {
                     exe.step.dependOn(&write_src.step);
                 }
 
-                const run_and_cmp_output = RunCompareOutputStep.create(self, exe.getOutputPath(), annotated_case_name, case.expected_output, case.cli_args);
-                run_and_cmp_output.step.dependOn(&exe.step);
+                const run_and_cmp_output = RunCompareOutputStep.create(
+                    self,
+                    exe,
+                    annotated_case_name,
+                    case.expected_output,
+                    case.cli_args,
+                );
 
                 self.step.dependOn(&run_and_cmp_output.step);
             },
@@ -490,8 +502,13 @@ pub const CompareOutputContext = struct {
                         exe.step.dependOn(&write_src.step);
                     }
 
-                    const run_and_cmp_output = RunCompareOutputStep.create(self, exe.getOutputPath(), annotated_case_name, case.expected_output, case.cli_args);
-                    run_and_cmp_output.step.dependOn(&exe.step);
+                    const run_and_cmp_output = RunCompareOutputStep.create(
+                        self,
+                        exe,
+                        annotated_case_name,
+                        case.expected_output,
+                        case.cli_args,
+                    );
 
                     self.step.dependOn(&run_and_cmp_output.step);
                 }
@@ -516,8 +533,7 @@ pub const CompareOutputContext = struct {
                     exe.step.dependOn(&write_src.step);
                 }
 
-                const run_and_cmp_output = RuntimeSafetyRunStep.create(self, exe.getOutputPath(), annotated_case_name);
-                run_and_cmp_output.step.dependOn(&exe.step);
+                const run_and_cmp_output = RuntimeSafetyRunStep.create(self, exe, annotated_case_name);
 
                 self.step.dependOn(&run_and_cmp_output.step);
             },
@@ -608,10 +624,6 @@ pub const CompileErrorContext = struct {
                 b.allocator,
                 [][]const u8{ b.cache_root, self.case.sources.items[0].filename },
             ) catch unreachable;
-            const obj_path = os.path.join(
-                b.allocator,
-                [][]const u8{ b.cache_root, "test.o" },
-            ) catch unreachable;
 
             var zig_args = ArrayList([]const u8).init(b.allocator);
             zig_args.append(b.zig_exe) catch unreachable;
@@ -628,8 +640,8 @@ pub const CompileErrorContext = struct {
             zig_args.append("--name") catch unreachable;
             zig_args.append("test") catch unreachable;
 
-            zig_args.append("--output") catch unreachable;
-            zig_args.append(b.pathFromRoot(obj_path)) catch unreachable;
+            zig_args.append("--output-dir") catch unreachable;
+            zig_args.append(b.pathFromRoot(b.cache_root)) catch unreachable;
 
             switch (self.build_mode) {
                 Mode.Debug => {},
@@ -851,7 +863,7 @@ pub const BuildExamplesContext = struct {
             zig_args.append("--verbose") catch unreachable;
         }
 
-        const run_cmd = b.addCommand(null, b.env_map, zig_args.toSliceConst());
+        const run_cmd = b.addSystemCommand(zig_args.toSliceConst());
 
         const log_step = b.addLog("PASS {}\n", annotated_case_name);
         log_step.step.dependOn(&run_cmd.step);
@@ -1118,23 +1130,28 @@ pub const GenHContext = struct {
     const GenHCmpOutputStep = struct {
         step: build.Step,
         context: *GenHContext,
-        h_path: []const u8,
+        obj: *LibExeObjStep,
         name: []const u8,
         test_index: usize,
         case: *const TestCase,
 
-        pub fn create(context: *GenHContext, h_path: []const u8, name: []const u8, case: *const TestCase) *GenHCmpOutputStep {
+        pub fn create(
+            context: *GenHContext,
+            obj: *LibExeObjStep,
+            name: []const u8,
+            case: *const TestCase,
+        ) *GenHCmpOutputStep {
             const allocator = context.b.allocator;
             const ptr = allocator.create(GenHCmpOutputStep) catch unreachable;
             ptr.* = GenHCmpOutputStep{
                 .step = build.Step.init("ParseCCmpOutput", allocator, make),
                 .context = context,
-                .h_path = h_path,
+                .obj = obj,
                 .name = name,
                 .test_index = context.test_index,
                 .case = case,
             };
-
+            ptr.step.dependOn(&obj.step);
             context.test_index += 1;
             return ptr;
         }
@@ -1145,7 +1162,7 @@ pub const GenHContext = struct {
 
             warn("Test {}/{} {}...", self.test_index + 1, self.context.test_index, self.name);
 
-            const full_h_path = b.pathFromRoot(self.h_path);
+            const full_h_path = self.obj.getOutputHPath();
             const actual_h = try io.readFileAlloc(b.allocator, full_h_path);
 
             for (self.case.expected_lines.toSliceConst()) |expected_line| {
@@ -1218,8 +1235,7 @@ pub const GenHContext = struct {
             obj.step.dependOn(&write_src.step);
         }
 
-        const cmp_h = GenHCmpOutputStep.create(self, obj.getOutputHPath(), annotated_case_name, case);
-        cmp_h.step.dependOn(&obj.step);
+        const cmp_h = GenHCmpOutputStep.create(self, obj, annotated_case_name, case);
 
         self.step.dependOn(&cmp_h.step);
     }