diff --git a/CMakeLists.txt b/CMakeLists.txt
index b460037e29..9492d5dfac 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -444,6 +444,7 @@ set(ZIG_STD_FILES
     "buffer.zig"
     "build.zig"
     "c/darwin.zig"
+    "c/freebsd.zig"
     "c/index.zig"
     "c/linux.zig"
     "c/windows.zig"
@@ -582,6 +583,10 @@ set(ZIG_STD_FILES
     "os/linux/vdso.zig"
     "os/linux/x86_64.zig"
     "os/linux/arm64.zig"
+    "os/freebsd/errno.zig"
+    "os/freebsd/index.zig"
+    "os/freebsd/syscall.zig"
+    "os/freebsd/x86_64.zig"
     "os/path.zig"
     "os/time.zig"
     "os/windows/advapi32.zig"
diff --git a/build.zig b/build.zig
index bb4aa30f97..e411ae8b21 100644
--- a/build.zig
+++ b/build.zig
@@ -297,7 +297,7 @@ fn configureStage2(b: *Builder, exe: var, ctx: Context) !void {
         );
 
         exe.linkSystemLibrary("pthread");
-    } else if (exe.target.isDarwin()) {
+    } else if (exe.target.isDarwin() or exe.target.isFreeBSD()) {
         if (addCxxKnownPath(b, ctx, exe, "libgcc_eh.a", "")) {
             // Compiler is GCC.
             try addCxxKnownPath(b, ctx, exe, "libstdc++.a", null);
diff --git a/cmake/Findclang.cmake b/cmake/Findclang.cmake
index ea1bc91d7b..9268f19730 100644
--- a/cmake/Findclang.cmake
+++ b/cmake/Findclang.cmake
@@ -30,6 +30,7 @@ else()
           /usr/lib/llvm/7/include
           /usr/lib/llvm-7/include
           /usr/lib/llvm-7.0/include
+          /usr/local/llvm70/include
           /mingw64/include)
 
       macro(FIND_AND_ADD_CLANG_LIB _libname_)
@@ -40,6 +41,7 @@ else()
               /usr/lib/llvm/7/lib
               /usr/lib/llvm-7/lib
               /usr/lib/llvm-7.0/lib
+              /usr/local/llvm70/lib
               /mingw64/lib
               /c/msys64/mingw64/lib
               c:\\msys64\\mingw64\\lib)
diff --git a/cmake/Findlld.cmake b/cmake/Findlld.cmake
index 1c4e9163a3..4e5b0c9a19 100644
--- a/cmake/Findlld.cmake
+++ b/cmake/Findlld.cmake
@@ -9,9 +9,13 @@
 find_path(LLD_INCLUDE_DIRS NAMES lld/Common/Driver.h
     PATHS
         /usr/lib/llvm-6.0/include
+        /usr/local/llvm60/include
         /mingw64/include)
 
-find_library(LLD_LIBRARY NAMES lld-6.0 lld PATHS /usr/lib/llvm-6.0/lib)
+find_library(LLD_LIBRARY NAMES lld-6.0 lld60 lld
+    PATHS
+        /usr/lib/llvm-6.0/lib
+        /usr/local/llvm70/lib)
 if(EXISTS ${LLD_LIBRARY})
     set(LLD_LIBRARIES ${LLD_LIBRARY})
 else()
@@ -20,6 +24,7 @@ else()
         find_library(LLD_${_prettylibname_}_LIB NAMES ${_libname_}
             PATHS
                 /usr/lib/llvm-6.0/lib
+                /usr/local/llvm70/lib
                 /mingw64/lib
                 /c/msys64/mingw64/lib
                 c:/msys64/mingw64/lib)
diff --git a/cmake/Findllvm.cmake b/cmake/Findllvm.cmake
index 150f2a2528..b847813682 100644
--- a/cmake/Findllvm.cmake
+++ b/cmake/Findllvm.cmake
@@ -8,7 +8,7 @@
 # LLVM_LIBDIRS
 
 find_program(LLVM_CONFIG_EXE
-    NAMES llvm-config-7 llvm-config-7.0 llvm-config
+    NAMES llvm-config-7 llvm-config-7.0 llvm-config70 llvm-config
     PATHS
         "/mingw64/bin"
         "/c/msys64/mingw64/bin"
diff --git a/src-self-hosted/libc_installation.zig b/src-self-hosted/libc_installation.zig
index 9f603fd9e8..1c5d111c5a 100644
--- a/src-self-hosted/libc_installation.zig
+++ b/src-self-hosted/libc_installation.zig
@@ -172,7 +172,7 @@ pub const LibCInstallation = struct {
                 try group.call(findNativeStaticLibDir, self, loop);
                 try group.call(findNativeDynamicLinker, self, loop);
             },
-            builtin.Os.macosx => {
+            builtin.Os.macosx, builtin.Os.freebsd => {
                 self.include_dir = try std.mem.dupe(loop.allocator, u8, "/usr/include");
             },
             else => @compileError("unimplemented: find libc for this OS"),
diff --git a/src-self-hosted/target.zig b/src-self-hosted/target.zig
index 6fe589ae52..eae0a12325 100644
--- a/src-self-hosted/target.zig
+++ b/src-self-hosted/target.zig
@@ -299,6 +299,13 @@ pub const Target = union(enum) {
     pub fn getDynamicLinkerPath(self: Target) ?[]const u8 {
         const env = self.getEnviron();
         const arch = self.getArch();
+        const os = self.getOs();
+        switch (os) {
+            builtin.Os.freebsd => {
+                return "/libexec/ld-elf.so.1";
+            },
+            else => {},
+        }
         switch (env) {
             builtin.Environ.android => {
                 if (self.is64bit()) {
@@ -493,6 +500,7 @@ pub const Target = union(enum) {
 
             builtin.Os.linux,
             builtin.Os.macosx,
+            builtin.Os.freebsd,
             builtin.Os.openbsd,
             builtin.Os.zen,
             => switch (id) {
@@ -527,7 +535,6 @@ pub const Target = union(enum) {
             builtin.Os.ananas,
             builtin.Os.cloudabi,
             builtin.Os.dragonfly,
-            builtin.Os.freebsd,
             builtin.Os.fuchsia,
             builtin.Os.ios,
             builtin.Os.kfreebsd,
diff --git a/src/analyze.cpp b/src/analyze.cpp
index 349169f9d1..076b281073 100644
--- a/src/analyze.cpp
+++ b/src/analyze.cpp
@@ -4579,7 +4579,10 @@ void find_libc_include_path(CodeGen *g) {
                 fprintf(stderr, "Unable to determine libc include path. --libc-include-dir");
                 exit(1);
             }
-        } else if (g->zig_target.os == OsLinux || g->zig_target.os == OsMacOSX) {
+        } else if (g->zig_target.os == OsLinux ||
+            g->zig_target.os == OsMacOSX ||
+            g->zig_target.os == OsFreeBSD)
+        {
             g->libc_include_dir = get_posix_libc_include_path();
         } else {
             fprintf(stderr, "Unable to determine libc include path.\n"
@@ -4627,6 +4630,8 @@ void find_libc_lib_path(CodeGen *g) {
 
         } else if (g->zig_target.os == OsLinux) {
             g->libc_lib_dir = get_linux_libc_lib_path("crt1.o");
+        } else if (g->zig_target.os == OsFreeBSD) {
+            g->libc_lib_dir = buf_create_from_str("/usr/lib");
         } else {
             zig_panic("Unable to determine libc lib path.");
         }
@@ -4639,6 +4644,8 @@ void find_libc_lib_path(CodeGen *g) {
             return;
         } else if (g->zig_target.os == OsLinux) {
             g->libc_static_lib_dir = get_linux_libc_lib_path("crtbegin.o");
+        } else if (g->zig_target.os == OsFreeBSD) {
+            g->libc_static_lib_dir = buf_create_from_str("/usr/lib");
         } else {
             zig_panic("Unable to determine libc static lib path.");
         }
diff --git a/src/link.cpp b/src/link.cpp
index 0e729fa918..188f976a86 100644
--- a/src/link.cpp
+++ b/src/link.cpp
@@ -150,6 +150,10 @@ static const char *getLDMOption(const ZigTarget *t) {
             if (t->env_type == ZigLLVM_GNUX32) {
                 return "elf32_x86_64";
             }
+            // Any target elf will use the freebsd osabi if suffixed with "_fbsd".
+            if (t->os == OsFreeBSD) {
+                return "elf_x86_64_fbsd";
+            }
             return "elf_x86_64";
         default:
             zig_unreachable();
@@ -191,6 +195,9 @@ static Buf *try_dynamic_linker_path(const char *ld_name) {
 }
 
 static Buf *get_dynamic_linker_path(CodeGen *g) {
+    if (g->zig_target.os == OsFreeBSD) {
+        return buf_create_from_str("/libexec/ld-elf.so.1");
+    }
     if (g->is_native_target && g->zig_target.arch.arch == ZigLLVM_x86_64) {
         static const char *ld_names[] = {
             "ld-linux-x86-64.so.2",
diff --git a/src/os.cpp b/src/os.cpp
index 5d43e73d8a..a323ef2cf5 100644
--- a/src/os.cpp
+++ b/src/os.cpp
@@ -50,10 +50,13 @@ typedef SSIZE_T ssize_t;
 
 #endif
 
-#if defined(ZIG_OS_LINUX)
+#if defined(ZIG_OS_LINUX) || defined(ZIG_OS_FREEBSD)
 #include <link.h>
 #endif
 
+#if defined(ZIG_OS_FREEBSD)
+#include <sys/sysctl.h>
+#endif
 
 #if defined(__MACH__)
 #include <mach/clock.h>
@@ -75,7 +78,9 @@ static clock_serv_t cclock;
 #if defined(__APPLE__) && !defined(environ)
 #include <crt_externs.h>
 #define environ (*_NSGetEnviron())
-#endif 
+#elif defined(ZIG_OS_FREEBSD)
+extern char **environ;
+#endif
 
 #if defined(ZIG_OS_POSIX)
 static void populate_termination(Termination *term, int status) {
@@ -1438,6 +1443,15 @@ Error os_self_exe_path(Buf *out_path) {
     }
     buf_resize(out_path, amt);
     return ErrorNone;
+#elif defined(ZIG_OS_FREEBSD)
+    buf_resize(out_path, PATH_MAX);
+    int mib[4] = { CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1 };
+    size_t cb = PATH_MAX;
+    if (sysctl(mib, 4, buf_ptr(out_path), &cb, nullptr, 0) != 0) {
+        return ErrorUnexpected;
+    }
+    buf_resize(out_path, cb);
+    return ErrorNone;
 #endif
     return ErrorFileNotFound;
 }
@@ -1743,7 +1757,7 @@ Error os_get_app_data_dir(Buf *out_path, const char *appname) {
     buf_resize(out_path, 0);
     buf_appendf(out_path, "%s/Library/Application Support/%s", home_dir, appname);
     return ErrorNone;
-#elif defined(ZIG_OS_LINUX)
+#elif defined(ZIG_OS_POSIX)
     const char *home_dir = getenv("HOME");
     if (home_dir == nullptr) {
         // TODO use /etc/passwd
@@ -1756,7 +1770,7 @@ Error os_get_app_data_dir(Buf *out_path, const char *appname) {
 }
 
 
-#if defined(ZIG_OS_LINUX)
+#if defined(ZIG_OS_LINUX) || defined(ZIG_OS_FREEBSD)
 static int self_exe_shared_libs_callback(struct dl_phdr_info *info, size_t size, void *data) {
     ZigList<Buf *> *libs = reinterpret_cast< ZigList<Buf *> *>(data);
     if (info->dlpi_name[0] == '/') {
@@ -1767,7 +1781,7 @@ static int self_exe_shared_libs_callback(struct dl_phdr_info *info, size_t size,
 #endif
 
 Error os_self_exe_shared_libs(ZigList<Buf *> &paths) {
-#if defined(ZIG_OS_LINUX)
+#if defined(ZIG_OS_LINUX) || defined(ZIG_OS_FREEBSD)
     paths.resize(0);
     dl_iterate_phdr(self_exe_shared_libs_callback, &paths);
     return ErrorNone;
@@ -1936,7 +1950,7 @@ Error os_file_mtime(OsFile file, OsTimeStamp *mtime) {
     mtime->sec = (((ULONGLONG) last_write_time.dwHighDateTime) << 32) + last_write_time.dwLowDateTime;
     mtime->nsec = 0;
     return ErrorNone;
-#elif defined(ZIG_OS_LINUX)
+#elif defined(ZIG_OS_LINUX) || defined(ZIG_OS_FREEBSD)
     struct stat statbuf;
     if (fstat(file, &statbuf) == -1)
         return ErrorFileSystem;
diff --git a/src/os.hpp b/src/os.hpp
index c3e77b8a1a..d81a2362a5 100644
--- a/src/os.hpp
+++ b/src/os.hpp
@@ -23,6 +23,8 @@
 #define ZIG_OS_WINDOWS
 #elif defined(__linux__)
 #define ZIG_OS_LINUX
+#elif defined(__FreeBSD__)
+#define ZIG_OS_FREEBSD
 #else
 #define ZIG_OS_UNKNOWN
 #endif
diff --git a/src/target.cpp b/src/target.cpp
index 7075c8a5c7..5a4b5252f1 100644
--- a/src/target.cpp
+++ b/src/target.cpp
@@ -738,6 +738,7 @@ uint32_t target_c_type_size_in_bits(const ZigTarget *target, CIntType id) {
         case OsLinux:
         case OsMacOSX:
         case OsZen:
+        case OsFreeBSD:
         case OsOpenBSD:
             switch (id) {
                 case CIntTypeShort:
@@ -774,7 +775,6 @@ uint32_t target_c_type_size_in_bits(const ZigTarget *target, CIntType id) {
         case OsAnanas:
         case OsCloudABI:
         case OsDragonFly:
-        case OsFreeBSD:
         case OsIOS:
         case OsKFreeBSD:
         case OsLv2:
diff --git a/src/util.cpp b/src/util.cpp
index 192d74e766..f7bda86c42 100644
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -47,7 +47,7 @@ bool ptr_eq(const void *a, const void *b) {
 // Ported from std/mem.zig.
 bool SplitIterator_isSplitByte(SplitIterator *self, uint8_t byte) {
     for (size_t i = 0; i < self->split_bytes.len; i += 1) {
-        if (byte == self->split_bytes.ptr[i]) {
+        if (byte == self->split_bytes.ptr[i] || byte == 0) {
             return true;
         }
     }
diff --git a/std/build.zig b/std/build.zig
index fe84455cbe..5d894eeeb1 100644
--- a/std/build.zig
+++ b/std/build.zig
@@ -795,6 +795,13 @@ pub const Target = union(enum) {
         };
     }
 
+    pub fn isFreeBSD(self: *const Target) bool {
+        return switch (self.getOs()) {
+            builtin.Os.freebsd => true,
+            else => false,
+        };
+    }
+
     pub fn wantSharedLibSymLinks(self: *const Target) bool {
         return !self.isWindows();
     }
diff --git a/std/c/freebsd.zig b/std/c/freebsd.zig
new file mode 100644
index 0000000000..6eb34929b5
--- /dev/null
+++ b/std/c/freebsd.zig
@@ -0,0 +1,36 @@
+
+const timespec = @import("../os/freebsd/index.zig").timespec;
+
+extern "c" fn __error() *c_int;
+pub const _errno = __error;
+
+pub extern "c" fn kqueue() c_int;
+pub extern "c" fn kevent(
+    kq: c_int,
+    changelist: [*]const Kevent,
+    nchanges: c_int,
+    eventlist: [*]Kevent,
+    nevents: c_int,
+    timeout: ?*const timespec,
+) c_int;
+pub extern "c" fn sysctl(name: [*]c_int, namelen: c_uint, oldp: ?*c_void, oldlenp: ?*usize, newp: ?*c_void, newlen: usize) c_int;
+pub extern "c" fn sysctlbyname(name: [*]const u8, oldp: ?*c_void, oldlenp: ?*usize, newp: ?*c_void, newlen: usize) c_int;
+pub extern "c" fn sysctlnametomib(name: [*]const u8, mibp: ?*c_int, sizep: ?*usize) c_int;
+
+/// Renamed from `kevent` to `Kevent` to avoid conflict with function name.
+pub const Kevent = extern struct.{
+    ident: usize,
+    filter: i16,
+    flags: u16,
+    fflags: u32,
+    data: i64,
+    udata: usize,
+    // TODO ext
+};
+
+
+pub const pthread_attr_t = extern struct.{
+    __size: [56]u8,
+    __align: c_long,
+};
+
diff --git a/std/c/index.zig b/std/c/index.zig
index 6b20d718ef..4aab39d931 100644
--- a/std/c/index.zig
+++ b/std/c/index.zig
@@ -5,6 +5,7 @@ pub use switch (builtin.os) {
     Os.linux => @import("linux.zig"),
     Os.windows => @import("windows.zig"),
     Os.macosx, Os.ios => @import("darwin.zig"),
+    Os.freebsd => @import("freebsd.zig"),
     else => empty_import,
 };
 const empty_import = @import("../empty.zig");
diff --git a/std/debug/index.zig b/std/debug/index.zig
index b077bdb3b0..a3509b3117 100644
--- a/std/debug/index.zig
+++ b/std/debug/index.zig
@@ -1101,6 +1101,8 @@ pub const DebugInfo = switch (builtin.os) {
             self.elf.close();
         }
     },
+    builtin.Os.freebsd => struct.{
+    },
     else => @compileError("Unsupported OS"),
 };
 
diff --git a/std/event/fs.zig b/std/event/fs.zig
index 2ce3014178..1b8e1aa5dc 100644
--- a/std/event/fs.zig
+++ b/std/event/fs.zig
@@ -83,6 +83,7 @@ pub async fn pwritev(loop: *Loop, fd: os.FileHandle, data: []const []const u8, o
     switch (builtin.os) {
         builtin.Os.macosx,
         builtin.Os.linux,
+        builtin.Os.freebsd,
         => {
             const iovecs = try loop.allocator.alloc(os.posix.iovec_const, data.len);
             defer loop.allocator.free(iovecs);
@@ -219,6 +220,7 @@ pub async fn preadv(loop: *Loop, fd: os.FileHandle, data: []const []u8, offset:
     switch (builtin.os) {
         builtin.Os.macosx,
         builtin.Os.linux,
+        builtin.Os.freebsd,
         => {
             const iovecs = try loop.allocator.alloc(os.posix.iovec, data.len);
             defer loop.allocator.free(iovecs);
@@ -399,7 +401,7 @@ pub async fn openPosix(
 
 pub async fn openRead(loop: *Loop, path: []const u8) os.File.OpenError!os.FileHandle {
     switch (builtin.os) {
-        builtin.Os.macosx, builtin.Os.linux => {
+        builtin.Os.macosx, builtin.Os.linux, builtin.Os.freebsd => {
             const flags = posix.O_LARGEFILE | posix.O_RDONLY | posix.O_CLOEXEC;
             return await (async openPosix(loop, path, flags, os.File.default_mode) catch unreachable);
         },
@@ -427,6 +429,7 @@ pub async fn openWriteMode(loop: *Loop, path: []const u8, mode: os.File.Mode) os
     switch (builtin.os) {
         builtin.Os.macosx,
         builtin.Os.linux,
+        builtin.Os.freebsd,
         => {
             const flags = posix.O_LARGEFILE | posix.O_WRONLY | posix.O_CREAT | posix.O_CLOEXEC | posix.O_TRUNC;
             return await (async openPosix(loop, path, flags, os.File.default_mode) catch unreachable);
@@ -449,7 +452,7 @@ pub async fn openReadWrite(
     mode: os.File.Mode,
 ) os.File.OpenError!os.FileHandle {
     switch (builtin.os) {
-        builtin.Os.macosx, builtin.Os.linux => {
+        builtin.Os.macosx, builtin.Os.linux, builtin.Os.freebsd => {
             const flags = posix.O_LARGEFILE | posix.O_RDWR | posix.O_CREAT | posix.O_CLOEXEC;
             return await (async openPosix(loop, path, flags, mode) catch unreachable);
         },
@@ -477,7 +480,7 @@ pub const CloseOperation = struct {
     os_data: OsData,
 
     const OsData = switch (builtin.os) {
-        builtin.Os.linux, builtin.Os.macosx => OsDataPosix,
+        builtin.Os.linux, builtin.Os.macosx, builtin.Os.freebsd => OsDataPosix,
 
         builtin.Os.windows => struct {
             handle: ?os.FileHandle,
@@ -496,7 +499,7 @@ pub const CloseOperation = struct {
         self.* = CloseOperation{
             .loop = loop,
             .os_data = switch (builtin.os) {
-                builtin.Os.linux, builtin.Os.macosx => initOsDataPosix(self),
+                builtin.Os.linux, builtin.Os.macosx, builtin.Os.freebsd => initOsDataPosix(self),
                 builtin.Os.windows => OsData{ .handle = null },
                 else => @compileError("Unsupported OS"),
             },
@@ -525,6 +528,7 @@ pub const CloseOperation = struct {
         switch (builtin.os) {
             builtin.Os.linux,
             builtin.Os.macosx,
+            builtin.Os.freebsd,
             => {
                 if (self.os_data.have_fd) {
                     self.loop.posixFsRequest(&self.os_data.close_req_node);
@@ -546,6 +550,7 @@ pub const CloseOperation = struct {
         switch (builtin.os) {
             builtin.Os.linux,
             builtin.Os.macosx,
+            builtin.Os.freebsd,
             => {
                 self.os_data.close_req_node.data.msg.Close.fd = handle;
                 self.os_data.have_fd = true;
@@ -562,6 +567,7 @@ pub const CloseOperation = struct {
         switch (builtin.os) {
             builtin.Os.linux,
             builtin.Os.macosx,
+            builtin.Os.freebsd,
             => {
                 self.os_data.have_fd = false;
             },
@@ -576,6 +582,7 @@ pub const CloseOperation = struct {
         switch (builtin.os) {
             builtin.Os.linux,
             builtin.Os.macosx,
+            builtin.Os.freebsd,
             => {
                 assert(self.os_data.have_fd);
                 return self.os_data.close_req_node.data.msg.Close.fd;
@@ -599,6 +606,7 @@ pub async fn writeFileMode(loop: *Loop, path: []const u8, contents: []const u8,
     switch (builtin.os) {
         builtin.Os.linux,
         builtin.Os.macosx,
+        builtin.Os.freebsd,
         => return await (async writeFileModeThread(loop, path, contents, mode) catch unreachable),
         builtin.Os.windows => return await (async writeFileWindows(loop, path, contents) catch unreachable),
         else => @compileError("Unsupported OS"),
@@ -704,7 +712,7 @@ pub fn Watch(comptime V: type) type {
         os_data: OsData,
 
         const OsData = switch (builtin.os) {
-            builtin.Os.macosx => struct {
+            builtin.Os.macosx, builtin.Os.freebsd => struct {
                 file_table: FileTable,
                 table_lock: event.Lock,
 
@@ -793,7 +801,7 @@ pub fn Watch(comptime V: type) type {
                     return self;
                 },
 
-                builtin.Os.macosx => {
+                builtin.Os.macosx, builtin.Os.freebsd => {
                     const self = try loop.allocator.createOne(Self);
                     errdefer loop.allocator.destroy(self);
 
@@ -813,7 +821,7 @@ pub fn Watch(comptime V: type) type {
         /// All addFile calls and removeFile calls must have completed.
         pub fn destroy(self: *Self) void {
             switch (builtin.os) {
-                builtin.Os.macosx => {
+                builtin.Os.macosx, builtin.Os.freebsd => {
                     // TODO we need to cancel the coroutines before destroying the lock
                     self.os_data.table_lock.deinit();
                     var it = self.os_data.file_table.iterator();
@@ -855,14 +863,14 @@ pub fn Watch(comptime V: type) type {
 
         pub async fn addFile(self: *Self, file_path: []const u8, value: V) !?V {
             switch (builtin.os) {
-                builtin.Os.macosx => return await (async addFileMacosx(self, file_path, value) catch unreachable),
+                builtin.Os.macosx, builtin.Os.freebsd => return await (async addFileKEvent(self, file_path, value) catch unreachable),
                 builtin.Os.linux => return await (async addFileLinux(self, file_path, value) catch unreachable),
                 builtin.Os.windows => return await (async addFileWindows(self, file_path, value) catch unreachable),
                 else => @compileError("Unsupported OS"),
             }
         }
 
-        async fn addFileMacosx(self: *Self, file_path: []const u8, value: V) !?V {
+        async fn addFileKEvent(self: *Self, file_path: []const u8, value: V) !?V {
             const resolved_path = try os.path.resolve(self.channel.loop.allocator, file_path);
             var resolved_path_consumed = false;
             defer if (!resolved_path_consumed) self.channel.loop.allocator.free(resolved_path);
@@ -871,7 +879,10 @@ pub fn Watch(comptime V: type) type {
             var close_op_consumed = false;
             defer if (!close_op_consumed) close_op.finish();
 
-            const flags = posix.O_SYMLINK | posix.O_EVTONLY;
+            const flags = switch (builtin.os) {
+                builtin.Os.macosx => posix.O_SYMLINK | posix.O_EVTONLY,
+                else => 0,
+            };
             const mode = 0;
             const fd = try await (async openPosix(self.channel.loop, resolved_path, flags, mode) catch unreachable);
             close_op.setHandle(fd);
diff --git a/std/event/loop.zig b/std/event/loop.zig
index fb47a9f253..43965e8293 100644
--- a/std/event/loop.zig
+++ b/std/event/loop.zig
@@ -49,7 +49,7 @@ pub const Loop = struct {
         };
 
         pub const EventFd = switch (builtin.os) {
-            builtin.Os.macosx => MacOsEventFd,
+            builtin.Os.macosx, builtin.Os.freebsd => KEventFd,
             builtin.Os.linux => struct {
                 base: ResumeNode,
                 epoll_op: u32,
@@ -62,13 +62,13 @@ pub const Loop = struct {
             else => @compileError("unsupported OS"),
         };
 
-        const MacOsEventFd = struct {
+        const KEventFd = struct {
             base: ResumeNode,
             kevent: posix.Kevent,
         };
 
         pub const Basic = switch (builtin.os) {
-            builtin.Os.macosx => MacOsBasic,
+            builtin.Os.macosx, builtin.Os.freebsd => KEventBasic,
             builtin.Os.linux => struct {
                 base: ResumeNode,
             },
@@ -78,7 +78,7 @@ pub const Loop = struct {
             else => @compileError("unsupported OS"),
         };
 
-        const MacOsBasic = struct {
+        const KEventBasic = struct {
             base: ResumeNode,
             kev: posix.Kevent,
         };
@@ -214,7 +214,7 @@ pub const Loop = struct {
                     self.extra_threads[extra_thread_index] = try os.spawnThread(self, workerRun);
                 }
             },
-            builtin.Os.macosx => {
+            builtin.Os.macosx, builtin.Os.freebsd => {
                 self.os_data.kqfd = try os.bsdKQueue();
                 errdefer os.close(self.os_data.kqfd);
 
@@ -369,7 +369,7 @@ pub const Loop = struct {
                 os.close(self.os_data.epollfd);
                 self.allocator.free(self.eventfd_resume_nodes);
             },
-            builtin.Os.macosx => {
+            builtin.Os.macosx, builtin.Os.freebsd => {
                 os.close(self.os_data.kqfd);
                 os.close(self.os_data.fs_kqfd);
             },
@@ -484,7 +484,7 @@ pub const Loop = struct {
             const eventfd_node = &resume_stack_node.data;
             eventfd_node.base.handle = next_tick_node.data;
             switch (builtin.os) {
-                builtin.Os.macosx => {
+                builtin.Os.macosx, builtin.Os.freebsd => {
                     const kevent_array = (*[1]posix.Kevent)(&eventfd_node.kevent);
                     const empty_kevs = ([*]posix.Kevent)(undefined)[0..0];
                     _ = os.bsdKEvent(self.os_data.kqfd, kevent_array, empty_kevs, null) catch {
@@ -546,6 +546,7 @@ pub const Loop = struct {
         switch (builtin.os) {
             builtin.Os.linux,
             builtin.Os.macosx,
+            builtin.Os.freebsd,
             => self.os_data.fs_thread.wait(),
             else => {},
         }
@@ -610,7 +611,7 @@ pub const Loop = struct {
                     os.posixWrite(self.os_data.final_eventfd, wakeup_bytes) catch unreachable;
                     return;
                 },
-                builtin.Os.macosx => {
+                builtin.Os.macosx, builtin.Os.freebsd => {
                     self.posixFsRequest(&self.os_data.fs_end_request);
                     const final_kevent = (*[1]posix.Kevent)(&self.os_data.final_kevent);
                     const empty_kevs = ([*]posix.Kevent)(undefined)[0..0];
@@ -668,7 +669,7 @@ pub const Loop = struct {
                         }
                     }
                 },
-                builtin.Os.macosx => {
+                builtin.Os.macosx, builtin.Os.freebsd => {
                     var eventlist: [1]posix.Kevent = undefined;
                     const empty_kevs = ([*]posix.Kevent)(undefined)[0..0];
                     const count = os.bsdKEvent(self.os_data.kqfd, empty_kevs, eventlist[0..], null) catch unreachable;
@@ -731,7 +732,7 @@ pub const Loop = struct {
         self.beginOneEvent(); // finished in posixFsRun after processing the msg
         self.os_data.fs_queue.put(request_node);
         switch (builtin.os) {
-            builtin.Os.macosx => {
+            builtin.Os.macosx, builtin.Os.freebsd => {
                 const fs_kevs = (*[1]posix.Kevent)(&self.os_data.fs_kevent_wake);
                 const empty_kevs = ([*]posix.Kevent)(undefined)[0..0];
                 _ = os.bsdKEvent(self.os_data.fs_kqfd, fs_kevs, empty_kevs, null) catch unreachable;
@@ -801,7 +802,7 @@ pub const Loop = struct {
                         else => unreachable,
                     }
                 },
-                builtin.Os.macosx => {
+                builtin.Os.macosx, builtin.Os.freebsd => {
                     const fs_kevs = (*[1]posix.Kevent)(&self.os_data.fs_kevent_wait);
                     var out_kevs: [1]posix.Kevent = undefined;
                     _ = os.bsdKEvent(self.os_data.fs_kqfd, fs_kevs, out_kevs[0..], null) catch unreachable;
@@ -813,7 +814,7 @@ pub const Loop = struct {
 
     const OsData = switch (builtin.os) {
         builtin.Os.linux => LinuxOsData,
-        builtin.Os.macosx => MacOsData,
+        builtin.Os.macosx, builtin.Os.freebsd => KEventData,
         builtin.Os.windows => struct {
             io_port: windows.HANDLE,
             extra_thread_count: usize,
@@ -821,7 +822,7 @@ pub const Loop = struct {
         else => struct {},
     };
 
-    const MacOsData = struct {
+    const KEventData = struct {
         kqfd: i32,
         final_kevent: posix.Kevent,
         fs_kevent_wake: posix.Kevent,
diff --git a/std/heap.zig b/std/heap.zig
index 9dbae4b8e0..5c31d412cf 100644
--- a/std/heap.zig
+++ b/std/heap.zig
@@ -70,7 +70,7 @@ pub const DirectAllocator = struct {
         const self = @fieldParentPtr(DirectAllocator, "allocator", allocator);
 
         switch (builtin.os) {
-            Os.linux, Os.macosx, Os.ios => {
+            Os.linux, Os.macosx, Os.ios, Os.freebsd => {
                 const p = os.posix;
                 const alloc_size = if (alignment <= os.page_size) n else n + alignment;
                 const addr = p.mmap(null, alloc_size, p.PROT_READ | p.PROT_WRITE, p.MAP_PRIVATE | p.MAP_ANONYMOUS, -1, 0);
@@ -121,7 +121,7 @@ pub const DirectAllocator = struct {
         const self = @fieldParentPtr(DirectAllocator, "allocator", allocator);
 
         switch (builtin.os) {
-            Os.linux, Os.macosx, Os.ios => {
+            Os.linux, Os.macosx, Os.ios, Os.freebsd => {
                 if (new_size <= old_mem.len) {
                     const base_addr = @ptrToInt(old_mem.ptr);
                     const old_addr_end = base_addr + old_mem.len;
@@ -166,7 +166,7 @@ pub const DirectAllocator = struct {
         const self = @fieldParentPtr(DirectAllocator, "allocator", allocator);
 
         switch (builtin.os) {
-            Os.linux, Os.macosx, Os.ios => {
+            Os.linux, Os.macosx, Os.ios, Os.freebsd => {
                 _ = os.posix.munmap(@ptrToInt(bytes.ptr), bytes.len);
             },
             Os.windows => {
diff --git a/std/os/file.zig b/std/os/file.zig
index 962428d4ca..82bd24fec0 100644
--- a/std/os/file.zig
+++ b/std/os/file.zig
@@ -230,7 +230,7 @@ pub const File = struct {
 
     pub fn seekForward(self: File, amount: isize) !void {
         switch (builtin.os) {
-            Os.linux, Os.macosx, Os.ios => {
+            Os.linux, Os.macosx, Os.ios, Os.freebsd => {
                 const result = posix.lseek(self.handle, amount, posix.SEEK_CUR);
                 const err = posix.getErrno(result);
                 if (err > 0) {
@@ -261,7 +261,7 @@ pub const File = struct {
 
     pub fn seekTo(self: File, pos: usize) !void {
         switch (builtin.os) {
-            Os.linux, Os.macosx, Os.ios => {
+            Os.linux, Os.macosx, Os.ios, Os.freebsd => {
                 const ipos = try math.cast(isize, pos);
                 const result = posix.lseek(self.handle, ipos, posix.SEEK_SET);
                 const err = posix.getErrno(result);
@@ -295,7 +295,7 @@ pub const File = struct {
 
     pub fn getPos(self: File) !usize {
         switch (builtin.os) {
-            Os.linux, Os.macosx, Os.ios => {
+            Os.linux, Os.macosx, Os.ios, Os.freebsd => {
                 const result = posix.lseek(self.handle, 0, posix.SEEK_CUR);
                 const err = posix.getErrno(result);
                 if (err > 0) {
diff --git a/std/os/freebsd/errno.zig b/std/os/freebsd/errno.zig
new file mode 100644
index 0000000000..0a0d825f5a
--- /dev/null
+++ b/std/os/freebsd/errno.zig
@@ -0,0 +1,121 @@
+pub const EPERM = 1; // Operation not permitted
+pub const ENOENT = 2; // No such file or directory
+pub const ESRCH = 3; // No such process
+pub const EINTR = 4; // Interrupted system call
+pub const EIO = 5; // Input/output error
+pub const ENXIO = 6; // Device not configured
+pub const E2BIG = 7; // Argument list too long
+pub const ENOEXEC = 8; // Exec format error
+pub const EBADF = 9; // Bad file descriptor
+pub const ECHILD = 10; // No child processes
+pub const EDEADLK = 11; // Resource deadlock avoided
+// 11 was EAGAIN
+pub const ENOMEM = 12; // Cannot allocate memory
+pub const EACCES = 13; // Permission denied
+pub const EFAULT = 14; // Bad address
+pub const ENOTBLK = 15; // Block device required
+pub const EBUSY = 16; // Device busy
+pub const EEXIST = 17; // File exists
+pub const EXDEV = 18; // Cross-device link
+pub const ENODEV = 19; // Operation not supported by device
+pub const ENOTDIR = 20; // Not a directory
+pub const EISDIR = 21; // Is a directory
+pub const EINVAL = 22; // Invalid argument
+pub const ENFILE = 23; // Too many open files in system
+pub const EMFILE = 24; // Too many open files
+pub const ENOTTY = 25; // Inappropriate ioctl for device
+pub const ETXTBSY = 26; // Text file busy
+pub const EFBIG = 27; // File too large
+pub const ENOSPC = 28; // No space left on device
+pub const ESPIPE = 29; // Illegal seek
+pub const EROFS = 30; // Read-only filesystem
+pub const EMLINK = 31; // Too many links
+pub const EPIPE = 32; // Broken pipe
+
+// math software
+pub const EDOM = 33; // Numerical argument out of domain
+pub const ERANGE = 34; // Result too large
+
+// non-blocking and interrupt i/o
+pub const EAGAIN = 35; // Resource temporarily unavailable
+pub const EWOULDBLOCK = EAGAIN; // Operation would block
+pub const EINPROGRESS = 36; // Operation now in progress
+pub const EALREADY = 37; // Operation already in progress
+
+// ipc/network software -- argument errors
+pub const ENOTSOCK = 38; // Socket operation on non-socket
+pub const EDESTADDRREQ = 39; // Destination address required
+pub const EMSGSIZE = 40; // Message too long
+pub const EPROTOTYPE = 41; // Protocol wrong type for socket
+pub const ENOPROTOOPT = 42; // Protocol not available
+pub const EPROTONOSUPPORT = 43; // Protocol not supported
+pub const ESOCKTNOSUPPORT = 44; // Socket type not supported
+pub const EOPNOTSUPP = 45; // Operation not supported
+pub const ENOTSUP = EOPNOTSUPP; // Operation not supported
+pub const EPFNOSUPPORT = 46; // Protocol family not supported
+pub const EAFNOSUPPORT = 47; // Address family not supported by protocol family
+pub const EADDRINUSE = 48; // Address already in use
+pub const EADDRNOTAVAIL = 49; // Can't assign requested address
+
+// ipc/network software -- operational errors
+pub const ENETDOWN = 50; // Network is down
+pub const ENETUNREACH = 51; // Network is unreachable
+pub const ENETRESET = 52; // Network dropped connection on reset
+pub const ECONNABORTED = 53; // Software caused connection abort
+pub const ECONNRESET = 54; // Connection reset by peer
+pub const ENOBUFS = 55; // No buffer space available
+pub const EISCONN = 56; // Socket is already connected
+pub const ENOTCONN = 57; // Socket is not connected
+pub const ESHUTDOWN = 58; // Can't send after socket shutdown
+pub const ETOOMANYREFS = 59; // Too many references: can't splice
+pub const ETIMEDOUT = 60; // Operation timed out
+pub const ECONNREFUSED = 61; // Connection refused
+
+pub const ELOOP = 62; // Too many levels of symbolic links
+pub const ENAMETOOLONG = 63; // File name too long
+
+// should be rearranged
+pub const EHOSTDOWN = 64; // Host is down
+pub const EHOSTUNREACH = 65; // No route to host
+pub const ENOTEMPTY = 66; // Directory not empty
+
+// quotas & mush
+pub const EPROCLIM = 67; // Too many processes
+pub const EUSERS = 68; // Too many users
+pub const EDQUOT = 69; // Disc quota exceeded
+
+// Network File System
+pub const ESTALE = 70; // Stale NFS file handle
+pub const EREMOTE = 71; // Too many levels of remote in path
+pub const EBADRPC = 72; // RPC struct is bad
+pub const ERPCMISMATCH = 73; // RPC version wrong
+pub const EPROGUNAVAIL = 74; // RPC prog. not avail
+pub const EPROGMISMATCH = 75; // Program version wrong
+pub const EPROCUNAVAIL = 76; // Bad procedure for program
+
+pub const ENOLCK = 77; // No locks available
+pub const ENOSYS = 78; // Function not implemented
+
+pub const EFTYPE = 79; // Inappropriate file type or format
+pub const EAUTH = 80; // Authentication error
+pub const ENEEDAUTH = 81; // Need authenticator
+pub const EIDRM = 82; // Identifier removed
+pub const ENOMSG = 83; // No message of desired type
+pub const EOVERFLOW = 84; // Value too large to be stored in data type
+pub const ECANCELED = 85; // Operation canceled
+pub const EILSEQ = 86; // Illegal byte sequence
+pub const ENOATTR = 87; // Attribute not found
+
+pub const EDOOFUS = 88; // Programming error
+
+pub const EBADMSG = 89; // Bad message
+pub const EMULTIHOP = 90; // Multihop attempted
+pub const ENOLINK = 91; // Link has been severed
+pub const EPROTO = 92; // Protocol error
+
+pub const ENOTCAPABLE = 93; // Capabilities insufficient
+pub const ECAPMODE = 94; // Not permitted in capability mode
+pub const ENOTRECOVERABLE = 95; // State not recoverable
+pub const EOWNERDEAD = 96; // Previous owner died
+
+pub const ELAST = 96; // Must be equal largest errno
diff --git a/std/os/freebsd/index.zig b/std/os/freebsd/index.zig
new file mode 100644
index 0000000000..1793379fb5
--- /dev/null
+++ b/std/os/freebsd/index.zig
@@ -0,0 +1,802 @@
+const assert = @import("../debug.zig").assert;
+const builtin = @import("builtin");
+const arch = switch (builtin.arch) {
+    builtin.Arch.x86_64 => @import("x86_64.zig"),
+    else => @compileError("unsupported arch"),
+};
+pub use @import("syscall.zig");
+pub use @import("errno.zig");
+
+const std = @import("../../index.zig");
+const c = std.c;
+pub const Kevent = c.Kevent;
+
+pub const PATH_MAX = 1024;
+
+pub const STDIN_FILENO = 0;
+pub const STDOUT_FILENO = 1;
+pub const STDERR_FILENO = 2;
+
+pub const PROT_NONE = 0;
+pub const PROT_READ = 1;
+pub const PROT_WRITE = 2;
+pub const PROT_EXEC = 4;
+
+pub const MAP_FAILED = @maxValue(usize);
+pub const MAP_SHARED = 0x0001;
+pub const MAP_PRIVATE = 0x0002;
+pub const MAP_FIXED = 0x0010;
+pub const MAP_STACK = 0x0400;
+pub const MAP_NOSYNC = 0x0800;
+pub const MAP_ANON = 0x1000;
+pub const MAP_ANONYMOUS = MAP_ANON;
+pub const MAP_FILE = 0;
+pub const MAP_NORESERVE = 0;
+
+pub const MAP_GUARD = 0x00002000;
+pub const MAP_EXCL = 0x00004000;
+pub const MAP_NOCORE = 0x00020000;
+pub const MAP_PREFAULT_READ = 0x00040000;
+pub const MAP_32BIT = 0x00080000;
+
+pub const WNOHANG = 1;
+pub const WUNTRACED = 2;
+pub const WSTOPPED = WUNTRACED;
+pub const WCONTINUED = 4;
+pub const WNOWAIT = 8;
+pub const WEXITED = 16;
+pub const WTRAPPED = 32;
+
+pub const SA_ONSTACK = 0x0001;
+pub const SA_RESTART = 0x0002;
+pub const SA_RESETHAND = 0x0004;
+pub const SA_NOCLDSTOP = 0x0008;
+pub const SA_NODEFER = 0x0010;
+pub const SA_NOCLDWAIT = 0x0020;
+pub const SA_SIGINFO = 0x0040;
+
+pub const SIGHUP = 1;
+pub const SIGINT = 2;
+pub const SIGQUIT = 3;
+pub const SIGILL = 4;
+pub const SIGTRAP = 5;
+pub const SIGABRT = 6;
+pub const SIGIOT = SIGABRT;
+pub const SIGEMT = 7;
+pub const SIGFPE = 8;
+pub const SIGKILL = 9;
+pub const SIGBUS = 10;
+pub const SIGSEGV = 11;
+pub const SIGSYS = 12;
+pub const SIGPIPE = 13;
+pub const SIGALRM = 14;
+pub const SIGTERM = 15;
+pub const SIGURG = 16;
+pub const SIGSTOP = 17;
+pub const SIGTSTP = 18;
+pub const SIGCONT = 19;
+pub const SIGCHLD = 20;
+pub const SIGTTIN = 21;
+pub const SIGTTOU = 22;
+pub const SIGIO = 23;
+pub const SIGXCPU = 24;
+pub const SIGXFSZ = 25;
+pub const SIGVTALRM = 26;
+pub const SIGPROF = 27;
+pub const SIGWINCH = 28;
+pub const SIGINFO = 29;
+pub const SIGUSR1 = 30;
+pub const SIGUSR2 = 31;
+pub const SIGTHR = 32;
+pub const SIGLWP = SIGTHR;
+pub const SIGLIBRT = 33;
+
+pub const SIGRTMIN = 65;
+pub const SIGRTMAX = 126;
+
+pub const O_RDONLY = 0o0;
+pub const O_WRONLY = 0o1;
+pub const O_RDWR = 0o2;
+pub const O_ACCMODE = 0o3;
+
+pub const O_CREAT = 0o100;
+pub const O_EXCL = 0o200;
+pub const O_NOCTTY = 0o400;
+pub const O_TRUNC = 0o1000;
+pub const O_APPEND = 0o2000;
+pub const O_NONBLOCK = 0o4000;
+pub const O_DSYNC = 0o10000;
+pub const O_SYNC = 0o4010000;
+pub const O_RSYNC = 0o4010000;
+pub const O_DIRECTORY = 0o200000;
+pub const O_NOFOLLOW = 0o400000;
+pub const O_CLOEXEC = 0o2000000;
+
+pub const O_ASYNC = 0o20000;
+pub const O_DIRECT = 0o40000;
+pub const O_LARGEFILE = 0;
+pub const O_NOATIME = 0o1000000;
+pub const O_PATH = 0o10000000;
+pub const O_TMPFILE = 0o20200000;
+pub const O_NDELAY = O_NONBLOCK;
+
+pub const F_DUPFD = 0;
+pub const F_GETFD = 1;
+pub const F_SETFD = 2;
+pub const F_GETFL = 3;
+pub const F_SETFL = 4;
+
+pub const F_SETOWN = 8;
+pub const F_GETOWN = 9;
+pub const F_SETSIG = 10;
+pub const F_GETSIG = 11;
+
+pub const F_GETLK = 5;
+pub const F_SETLK = 6;
+pub const F_SETLKW = 7;
+
+pub const F_SETOWN_EX = 15;
+pub const F_GETOWN_EX = 16;
+
+pub const F_GETOWNER_UIDS = 17;
+
+pub const SEEK_SET = 0;
+pub const SEEK_CUR = 1;
+pub const SEEK_END = 2;
+
+pub const SIG_BLOCK = 1;
+pub const SIG_UNBLOCK = 2;
+pub const SIG_SETMASK = 3;
+
+pub const SOCK_STREAM = 1;
+pub const SOCK_DGRAM = 2;
+pub const SOCK_RAW = 3;
+pub const SOCK_RDM = 4;
+pub const SOCK_SEQPACKET = 5;
+
+pub const SOCK_CLOEXEC = 0x10000000;
+pub const SOCK_NONBLOCK = 0x20000000;
+
+// TODO: From here
+pub const PROTO_ip = 0o000;
+pub const PROTO_icmp = 0o001;
+pub const PROTO_igmp = 0o002;
+pub const PROTO_ggp = 0o003;
+pub const PROTO_ipencap = 0o004;
+pub const PROTO_st = 0o005;
+pub const PROTO_tcp = 0o006;
+pub const PROTO_egp = 0o010;
+pub const PROTO_pup = 0o014;
+pub const PROTO_udp = 0o021;
+pub const PROTO_hmp = 0o024;
+pub const PROTO_xns_idp = 0o026;
+pub const PROTO_rdp = 0o033;
+pub const PROTO_iso_tp4 = 0o035;
+pub const PROTO_xtp = 0o044;
+pub const PROTO_ddp = 0o045;
+pub const PROTO_idpr_cmtp = 0o046;
+pub const PROTO_ipv6 = 0o051;
+pub const PROTO_ipv6_route = 0o053;
+pub const PROTO_ipv6_frag = 0o054;
+pub const PROTO_idrp = 0o055;
+pub const PROTO_rsvp = 0o056;
+pub const PROTO_gre = 0o057;
+pub const PROTO_esp = 0o062;
+pub const PROTO_ah = 0o063;
+pub const PROTO_skip = 0o071;
+pub const PROTO_ipv6_icmp = 0o072;
+pub const PROTO_ipv6_nonxt = 0o073;
+pub const PROTO_ipv6_opts = 0o074;
+pub const PROTO_rspf = 0o111;
+pub const PROTO_vmtp = 0o121;
+pub const PROTO_ospf = 0o131;
+pub const PROTO_ipip = 0o136;
+pub const PROTO_encap = 0o142;
+pub const PROTO_pim = 0o147;
+pub const PROTO_raw = 0o377;
+
+pub const PF_UNSPEC = 0;
+pub const PF_LOCAL = 1;
+pub const PF_UNIX = PF_LOCAL;
+pub const PF_FILE = PF_LOCAL;
+pub const PF_INET = 2;
+pub const PF_AX25 = 3;
+pub const PF_IPX = 4;
+pub const PF_APPLETALK = 5;
+pub const PF_NETROM = 6;
+pub const PF_BRIDGE = 7;
+pub const PF_ATMPVC = 8;
+pub const PF_X25 = 9;
+pub const PF_INET6 = 10;
+pub const PF_ROSE = 11;
+pub const PF_DECnet = 12;
+pub const PF_NETBEUI = 13;
+pub const PF_SECURITY = 14;
+pub const PF_KEY = 15;
+pub const PF_NETLINK = 16;
+pub const PF_ROUTE = PF_NETLINK;
+pub const PF_PACKET = 17;
+pub const PF_ASH = 18;
+pub const PF_ECONET = 19;
+pub const PF_ATMSVC = 20;
+pub const PF_RDS = 21;
+pub const PF_SNA = 22;
+pub const PF_IRDA = 23;
+pub const PF_PPPOX = 24;
+pub const PF_WANPIPE = 25;
+pub const PF_LLC = 26;
+pub const PF_IB = 27;
+pub const PF_MPLS = 28;
+pub const PF_CAN = 29;
+pub const PF_TIPC = 30;
+pub const PF_BLUETOOTH = 31;
+pub const PF_IUCV = 32;
+pub const PF_RXRPC = 33;
+pub const PF_ISDN = 34;
+pub const PF_PHONET = 35;
+pub const PF_IEEE802154 = 36;
+pub const PF_CAIF = 37;
+pub const PF_ALG = 38;
+pub const PF_NFC = 39;
+pub const PF_VSOCK = 40;
+pub const PF_MAX = 41;
+
+pub const AF_UNSPEC = PF_UNSPEC;
+pub const AF_LOCAL = PF_LOCAL;
+pub const AF_UNIX = AF_LOCAL;
+pub const AF_FILE = AF_LOCAL;
+pub const AF_INET = PF_INET;
+pub const AF_AX25 = PF_AX25;
+pub const AF_IPX = PF_IPX;
+pub const AF_APPLETALK = PF_APPLETALK;
+pub const AF_NETROM = PF_NETROM;
+pub const AF_BRIDGE = PF_BRIDGE;
+pub const AF_ATMPVC = PF_ATMPVC;
+pub const AF_X25 = PF_X25;
+pub const AF_INET6 = PF_INET6;
+pub const AF_ROSE = PF_ROSE;
+pub const AF_DECnet = PF_DECnet;
+pub const AF_NETBEUI = PF_NETBEUI;
+pub const AF_SECURITY = PF_SECURITY;
+pub const AF_KEY = PF_KEY;
+pub const AF_NETLINK = PF_NETLINK;
+pub const AF_ROUTE = PF_ROUTE;
+pub const AF_PACKET = PF_PACKET;
+pub const AF_ASH = PF_ASH;
+pub const AF_ECONET = PF_ECONET;
+pub const AF_ATMSVC = PF_ATMSVC;
+pub const AF_RDS = PF_RDS;
+pub const AF_SNA = PF_SNA;
+pub const AF_IRDA = PF_IRDA;
+pub const AF_PPPOX = PF_PPPOX;
+pub const AF_WANPIPE = PF_WANPIPE;
+pub const AF_LLC = PF_LLC;
+pub const AF_IB = PF_IB;
+pub const AF_MPLS = PF_MPLS;
+pub const AF_CAN = PF_CAN;
+pub const AF_TIPC = PF_TIPC;
+pub const AF_BLUETOOTH = PF_BLUETOOTH;
+pub const AF_IUCV = PF_IUCV;
+pub const AF_RXRPC = PF_RXRPC;
+pub const AF_ISDN = PF_ISDN;
+pub const AF_PHONET = PF_PHONET;
+pub const AF_IEEE802154 = PF_IEEE802154;
+pub const AF_CAIF = PF_CAIF;
+pub const AF_ALG = PF_ALG;
+pub const AF_NFC = PF_NFC;
+pub const AF_VSOCK = PF_VSOCK;
+pub const AF_MAX = PF_MAX;
+
+pub const DT_UNKNOWN = 0;
+pub const DT_FIFO = 1;
+pub const DT_CHR = 2;
+pub const DT_DIR = 4;
+pub const DT_BLK = 6;
+pub const DT_REG = 8;
+pub const DT_LNK = 10;
+pub const DT_SOCK = 12;
+pub const DT_WHT = 14;
+
+/// add event to kq (implies enable)
+pub const EV_ADD = 0x0001;
+
+/// delete event from kq
+pub const EV_DELETE = 0x0002;
+
+/// enable event
+pub const EV_ENABLE = 0x0004;
+
+/// disable event (not reported)
+pub const EV_DISABLE = 0x0008;
+
+/// only report one occurrence
+pub const EV_ONESHOT = 0x0010;
+
+/// clear event state after reporting
+pub const EV_CLEAR = 0x0020;
+
+/// force immediate event output
+/// ... with or without EV_ERROR
+/// ... use KEVENT_FLAG_ERROR_EVENTS
+///     on syscalls supporting flags
+pub const EV_RECEIPT = 0x0040;
+
+/// disable event after reporting
+pub const EV_DISPATCH = 0x0080;
+
+pub const EVFILT_READ = -1;
+pub const EVFILT_WRITE = -2;
+
+/// attached to aio requests
+pub const EVFILT_AIO = -3;
+
+/// attached to vnodes
+pub const EVFILT_VNODE = -4;
+
+/// attached to struct proc
+pub const EVFILT_PROC = -5;
+
+/// attached to struct proc
+pub const EVFILT_SIGNAL = -6;
+
+/// timers
+pub const EVFILT_TIMER = -7;
+
+/// Process descriptors
+pub const EVFILT_PROCDESC = -8;
+
+/// Filesystem events
+pub const EVFILT_FS = -9;
+
+pub const EVFILT_LIO = -10;
+
+/// User events
+pub const EVFILT_USER = -11;
+
+/// Sendfile events
+pub const EVFILT_SENDFILE = -12;
+
+pub const EVFILT_EMPTY = -13;
+
+/// On input, NOTE_TRIGGER causes the event to be triggered for output.
+pub const NOTE_TRIGGER = 0x01000000;
+
+/// ignore input fflags
+pub const NOTE_FFNOP = 0x00000000;
+
+/// and fflags
+pub const NOTE_FFAND = 0x40000000;
+
+/// or fflags
+pub const NOTE_FFOR = 0x80000000;
+
+/// copy fflags
+pub const NOTE_FFCOPY = 0xc0000000;
+
+/// mask for operations
+pub const NOTE_FFCTRLMASK = 0xc0000000;
+pub const NOTE_FFLAGSMASK = 0x00ffffff;
+
+
+/// low water mark
+pub const NOTE_LOWAT = 0x00000001;
+
+/// behave like poll()
+pub const NOTE_FILE_POLL = 0x00000002;
+
+/// vnode was removed
+pub const NOTE_DELETE = 0x00000001;
+
+/// data contents changed
+pub const NOTE_WRITE = 0x00000002;
+
+/// size increased
+pub const NOTE_EXTEND = 0x00000004;
+
+/// attributes changed
+pub const NOTE_ATTRIB = 0x00000008;
+
+/// link count changed
+pub const NOTE_LINK = 0x00000010;
+
+/// vnode was renamed
+pub const NOTE_RENAME = 0x00000020;
+
+/// vnode access was revoked
+pub const NOTE_REVOKE = 0x00000040;
+
+/// vnode was opened
+pub const NOTE_OPEN = 0x00000080;
+
+/// file closed, fd did not allow write
+pub const NOTE_CLOSE = 0x00000100;
+
+/// file closed, fd did allow write
+pub const NOTE_CLOSE_WRITE = 0x00000200;
+
+/// file was read
+pub const NOTE_READ = 0x00000400;
+
+/// process exited
+pub const NOTE_EXIT = 0x80000000;
+
+/// process forked
+pub const NOTE_FORK = 0x40000000;
+
+/// process exec'd
+pub const NOTE_EXEC = 0x20000000;
+
+/// mask for signal & exit status
+pub const NOTE_PDATAMASK = 0x000fffff;
+pub const NOTE_PCTRLMASK = (~NOTE_PDATAMASK);
+
+/// data is seconds
+pub const NOTE_SECONDS = 0x00000001;
+
+/// data is milliseconds
+pub const NOTE_MSECONDS = 0x00000002;
+
+/// data is microseconds
+pub const NOTE_USECONDS = 0x00000004;
+
+/// data is nanoseconds
+pub const NOTE_NSECONDS = 0x00000008;
+
+/// timeout is absolute
+pub const NOTE_ABSTIME = 0x00000010;
+
+
+
+pub const TCGETS = 0x5401;
+pub const TCSETS = 0x5402;
+pub const TCSETSW = 0x5403;
+pub const TCSETSF = 0x5404;
+pub const TCGETA = 0x5405;
+pub const TCSETA = 0x5406;
+pub const TCSETAW = 0x5407;
+pub const TCSETAF = 0x5408;
+pub const TCSBRK = 0x5409;
+pub const TCXONC = 0x540A;
+pub const TCFLSH = 0x540B;
+pub const TIOCEXCL = 0x540C;
+pub const TIOCNXCL = 0x540D;
+pub const TIOCSCTTY = 0x540E;
+pub const TIOCGPGRP = 0x540F;
+pub const TIOCSPGRP = 0x5410;
+pub const TIOCOUTQ = 0x5411;
+pub const TIOCSTI = 0x5412;
+pub const TIOCGWINSZ = 0x5413;
+pub const TIOCSWINSZ = 0x5414;
+pub const TIOCMGET = 0x5415;
+pub const TIOCMBIS = 0x5416;
+pub const TIOCMBIC = 0x5417;
+pub const TIOCMSET = 0x5418;
+pub const TIOCGSOFTCAR = 0x5419;
+pub const TIOCSSOFTCAR = 0x541A;
+pub const FIONREAD = 0x541B;
+pub const TIOCINQ = FIONREAD;
+pub const TIOCLINUX = 0x541C;
+pub const TIOCCONS = 0x541D;
+pub const TIOCGSERIAL = 0x541E;
+pub const TIOCSSERIAL = 0x541F;
+pub const TIOCPKT = 0x5420;
+pub const FIONBIO = 0x5421;
+pub const TIOCNOTTY = 0x5422;
+pub const TIOCSETD = 0x5423;
+pub const TIOCGETD = 0x5424;
+pub const TCSBRKP = 0x5425;
+pub const TIOCSBRK = 0x5427;
+pub const TIOCCBRK = 0x5428;
+pub const TIOCGSID = 0x5429;
+pub const TIOCGRS485 = 0x542E;
+pub const TIOCSRS485 = 0x542F;
+pub const TIOCGPTN = 0x80045430;
+pub const TIOCSPTLCK = 0x40045431;
+pub const TIOCGDEV = 0x80045432;
+pub const TCGETX = 0x5432;
+pub const TCSETX = 0x5433;
+pub const TCSETXF = 0x5434;
+pub const TCSETXW = 0x5435;
+pub const TIOCSIG = 0x40045436;
+pub const TIOCVHANGUP = 0x5437;
+pub const TIOCGPKT = 0x80045438;
+pub const TIOCGPTLCK = 0x80045439;
+pub const TIOCGEXCL = 0x80045440;
+
+fn unsigned(s: i32) u32 {
+    return @bitCast(u32, s);
+}
+fn signed(s: u32) i32 {
+    return @bitCast(i32, s);
+}
+pub fn WEXITSTATUS(s: i32) i32 {
+    return signed((unsigned(s) & 0xff00) >> 8);
+}
+pub fn WTERMSIG(s: i32) i32 {
+    return signed(unsigned(s) & 0x7f);
+}
+pub fn WSTOPSIG(s: i32) i32 {
+    return WEXITSTATUS(s);
+}
+pub fn WIFEXITED(s: i32) bool {
+    return WTERMSIG(s) == 0;
+}
+pub fn WIFSTOPPED(s: i32) bool {
+    return @intCast(u16, (((unsigned(s) & 0xffff) *% 0x10001) >> 8)) > 0x7f00;
+}
+pub fn WIFSIGNALED(s: i32) bool {
+    return (unsigned(s) & 0xffff) -% 1 < 0xff;
+}
+
+pub const winsize = extern struct.{
+    ws_row: u16,
+    ws_col: u16,
+    ws_xpixel: u16,
+    ws_ypixel: u16,
+};
+
+/// Get the errno from a syscall return value, or 0 for no error.
+pub fn getErrno(r: usize) usize {
+    const signed_r = @bitCast(isize, r);
+    return if (signed_r > -4096 and signed_r < 0) @intCast(usize, -signed_r) else 0;
+}
+
+pub fn dup2(old: i32, new: i32) usize {
+    return arch.syscall2(SYS_dup2, @intCast(usize, old), @intCast(usize, new));
+}
+
+pub fn chdir(path: [*]const u8) usize {
+    return arch.syscall1(SYS_chdir, @ptrToInt(path));
+}
+
+pub fn execve(path: [*]const u8, argv: [*]const ?[*]const u8, envp: [*]const ?[*]const u8) usize {
+    return arch.syscall3(SYS_execve, @ptrToInt(path), @ptrToInt(argv), @ptrToInt(envp));
+}
+
+pub fn fork() usize {
+    return arch.syscall0(SYS_fork);
+}
+
+pub fn getcwd(buf: [*]u8, size: usize) usize {
+    return arch.syscall2(SYS___getcwd, @ptrToInt(buf), size);
+}
+
+pub fn getdents(fd: i32, dirp: [*]u8, count: usize) usize {
+    return arch.syscall3(SYS_getdents, @intCast(usize, fd), @ptrToInt(dirp), count);
+}
+
+pub fn isatty(fd: i32) bool {
+    var wsz: winsize = undefined;
+    return arch.syscall3(SYS_ioctl, @intCast(usize, fd), TIOCGWINSZ, @ptrToInt(&wsz)) == 0;
+}
+
+pub fn readlink(noalias path: [*]const u8, noalias buf_ptr: [*]u8, buf_len: usize) usize {
+    return arch.syscall3(SYS_readlink, @ptrToInt(path), @ptrToInt(buf_ptr), buf_len);
+}
+
+pub fn mkdir(path: [*]const u8, mode: u32) usize {
+    return arch.syscall2(SYS_mkdir, @ptrToInt(path), mode);
+}
+
+pub fn mmap(address: ?*u8, length: usize, prot: usize, flags: usize, fd: i32, offset: isize) usize {
+    return arch.syscall6(SYS_mmap, @ptrToInt(address), length, prot, flags, @intCast(usize, fd), @bitCast(usize, offset));
+}
+
+pub fn munmap(address: usize, length: usize) usize {
+    return arch.syscall2(SYS_munmap, address, length);
+}
+
+pub fn read(fd: i32, buf: [*]u8, count: usize) usize {
+    return arch.syscall3(SYS_read, @intCast(usize, fd), @ptrToInt(buf), count);
+}
+
+pub fn rmdir(path: [*]const u8) usize {
+    return arch.syscall1(SYS_rmdir, @ptrToInt(path));
+}
+
+pub fn symlink(existing: [*]const u8, new: [*]const u8) usize {
+    return arch.syscall2(SYS_symlink, @ptrToInt(existing), @ptrToInt(new));
+}
+
+pub fn pread(fd: i32, buf: [*]u8, count: usize, offset: usize) usize {
+    return arch.syscall4(SYS_pread, @intCast(usize, fd), @ptrToInt(buf), count, offset);
+}
+
+pub fn preadv(fd: i32, iov: [*]const iovec, count: usize, offset: usize) usize {
+    return arch.syscall4(SYS_preadv, @intCast(usize, fd), @ptrToInt(iov), count, offset);
+}
+
+pub fn pipe(fd: *[2]i32) usize {
+    return pipe2(fd, 0);
+}
+
+pub fn pipe2(fd: *[2]i32, flags: usize) usize {
+    return arch.syscall2(SYS_pipe2, @ptrToInt(fd), flags);
+}
+
+pub fn write(fd: i32, buf: [*]const u8, count: usize) usize {
+    return arch.syscall3(SYS_write, @intCast(usize, fd), @ptrToInt(buf), count);
+}
+
+pub fn pwrite(fd: i32, buf: [*]const u8, count: usize, offset: usize) usize {
+    return arch.syscall4(SYS_pwrite, @intCast(usize, fd), @ptrToInt(buf), count, offset);
+}
+
+pub fn pwritev(fd: i32, iov: [*]const iovec_const, count: usize, offset: usize) usize {
+    return arch.syscall4(SYS_pwritev, @intCast(usize, fd), @ptrToInt(iov), count, offset);
+}
+
+pub fn rename(old: [*]const u8, new: [*]const u8) usize {
+    return arch.syscall2(SYS_rename, @ptrToInt(old), @ptrToInt(new));
+}
+
+pub fn open(path: [*]const u8, flags: u32, perm: usize) usize {
+    return arch.syscall3(SYS_open, @ptrToInt(path), flags, perm);
+}
+
+pub fn create(path: [*]const u8, perm: usize) usize {
+    return arch.syscall2(SYS_creat, @ptrToInt(path), perm);
+}
+
+pub fn openat(dirfd: i32, path: [*]const u8, flags: usize, mode: usize) usize {
+    return arch.syscall4(SYS_openat, @intCast(usize, dirfd), @ptrToInt(path), flags, mode);
+}
+
+pub fn close(fd: i32) usize {
+    return arch.syscall1(SYS_close, @intCast(usize, fd));
+}
+
+pub fn lseek(fd: i32, offset: isize, ref_pos: usize) usize {
+    return arch.syscall3(SYS_lseek, @intCast(usize, fd), @bitCast(usize, offset), ref_pos);
+}
+
+pub fn exit(status: i32) noreturn {
+    _ = arch.syscall1(SYS_exit, @bitCast(usize, isize(status)));
+    unreachable;
+}
+
+pub fn getrandom(buf: [*]u8, count: usize, flags: u32) usize {
+    return arch.syscall3(SYS_getrandom, @ptrToInt(buf), count, @intCast(usize, flags));
+}
+
+pub fn kill(pid: i32, sig: i32) usize {
+    return arch.syscall2(SYS_kill, @bitCast(usize, @intCast(isize, pid)), @intCast(usize, sig));
+}
+
+pub fn unlink(path: [*]const u8) usize {
+    return arch.syscall1(SYS_unlink, @ptrToInt(path));
+}
+
+pub fn waitpid(pid: i32, status: *i32, options: i32) usize {
+    return arch.syscall4(SYS_wait4, @bitCast(usize, isize(pid)), @ptrToInt(status), @bitCast(usize, isize(options)), 0);
+}
+
+pub fn nanosleep(req: *const timespec, rem: ?*timespec) usize {
+    return arch.syscall2(SYS_nanosleep, @ptrToInt(req), @ptrToInt(rem));
+}
+
+pub fn setuid(uid: u32) usize {
+    return arch.syscall1(SYS_setuid, uid);
+}
+
+pub fn setgid(gid: u32) usize {
+    return arch.syscall1(SYS_setgid, gid);
+}
+
+pub fn setreuid(ruid: u32, euid: u32) usize {
+    return arch.syscall2(SYS_setreuid, ruid, euid);
+}
+
+pub fn setregid(rgid: u32, egid: u32) usize {
+    return arch.syscall2(SYS_setregid, rgid, egid);
+}
+
+pub fn sigprocmask(flags: u32, noalias set: *const sigset_t, noalias oldset: ?*sigset_t) usize {
+    // TODO: Implement
+    return 0;
+}
+
+pub fn sigaction(sig: u6, noalias act: *const Sigaction, noalias oact: ?*Sigaction) usize {
+    // TODO: Implement
+    return 0;
+}
+
+const NSIG = 65;
+const sigset_t = [128 / @sizeOf(usize)]usize;
+const all_mask = []usize.{@maxValue(usize)};
+const app_mask = []usize.{0xfffffffc7fffffff};
+
+/// Renamed from `sigaction` to `Sigaction` to avoid conflict with the syscall.
+pub const Sigaction = struct.{
+    // TODO: Adjust to use freebsd struct layout
+    handler: extern fn (i32) void,
+    mask: sigset_t,
+    flags: u32,
+};
+
+pub const SIG_ERR = @intToPtr(extern fn (i32) void, @maxValue(usize));
+pub const SIG_DFL = @intToPtr(extern fn (i32) void, 0);
+pub const SIG_IGN = @intToPtr(extern fn (i32) void, 1);
+pub const empty_sigset = []usize.{0} ** sigset_t.len;
+
+pub fn raise(sig: i32) usize {
+    // TODO implement, see linux equivalent for what we want to try and do
+    return 0;
+}
+
+fn blockAllSignals(set: *sigset_t) void {
+    // TODO implement
+}
+
+fn blockAppSignals(set: *sigset_t) void {
+    // TODO implement
+}
+
+fn restoreSignals(set: *sigset_t) void {
+    // TODO implement
+}
+
+pub fn sigaddset(set: *sigset_t, sig: u6) void {
+    const s = sig - 1;
+    (*set)[usize(s) / usize.bit_count] |= usize(1) << (s & (usize.bit_count - 1));
+}
+
+pub fn sigismember(set: *const sigset_t, sig: u6) bool {
+    const s = sig - 1;
+    return ((*set)[usize(s) / usize.bit_count] & (usize(1) << (s & (usize.bit_count - 1)))) != 0;
+}
+
+pub const Stat = arch.Stat;
+pub const timespec = arch.timespec;
+
+pub fn fstat(fd: i32, stat_buf: *Stat) usize {
+    return arch.syscall2(SYS_fstat, @intCast(usize, fd), @ptrToInt(stat_buf));
+}
+
+pub const iovec = extern struct.{
+    iov_base: [*]u8,
+    iov_len: usize,
+};
+
+pub const iovec_const = extern struct.{
+    iov_base: [*]const u8,
+    iov_len: usize,
+};
+
+pub fn kqueue() usize {
+    return errnoWrap(c.kqueue());
+}
+
+pub fn kevent(kq: i32, changelist: []const Kevent, eventlist: []Kevent, timeout: ?*const timespec) usize {
+    return errnoWrap(c.kevent(
+        kq,
+        changelist.ptr,
+        @intCast(c_int, changelist.len),
+        eventlist.ptr,
+        @intCast(c_int, eventlist.len),
+        timeout,
+    ));
+}
+
+pub fn sysctl(name: [*]c_int, namelen: c_uint, oldp: ?*c_void, oldlenp: ?*usize, newp: ?*c_void, newlen: usize) usize {
+    return errnoWrap(c.sysctl(name, namelen, oldp, oldlenp, newp, newlen));
+}
+
+pub fn sysctlbyname(name: [*]const u8, oldp: ?*c_void, oldlenp: ?*usize, newp: ?*c_void, newlen: usize) usize {
+    return errnoWrap(c.sysctlbyname(name, oldp, oldlenp, newp, newlen));
+}
+
+pub fn sysctlnametomib(name: [*]const u8, mibp: ?*c_int, sizep: ?*usize) usize {
+    return errnoWrap(c.sysctlnametomib(name, wibp, sizep));
+}
+
+
+
+/// Takes the return value from a syscall and formats it back in the way
+/// that the kernel represents it to libc. Errno was a mistake, let's make
+/// it go away forever.
+fn errnoWrap(value: isize) usize {
+    return @bitCast(usize, if (value == -1) -isize(c._errno().*) else value);
+}
+
+
diff --git a/std/os/freebsd/syscall.zig b/std/os/freebsd/syscall.zig
new file mode 100644
index 0000000000..6cdd71de3b
--- /dev/null
+++ b/std/os/freebsd/syscall.zig
@@ -0,0 +1,493 @@
+pub const SYS_syscall = 0;
+pub const SYS_exit = 1;
+pub const SYS_fork = 2;
+pub const SYS_read = 3;
+pub const SYS_write = 4;
+pub const SYS_open = 5;
+pub const SYS_close = 6;
+pub const SYS_wait4 = 7;
+// 8 is old creat
+pub const SYS_link = 9;
+pub const SYS_unlink = 10;
+// 11 is obsolete execv
+pub const SYS_chdir = 12;
+pub const SYS_fchdir = 13;
+pub const SYS_freebsd11_mknod = 14;
+pub const SYS_chmod = 15;
+pub const SYS_chown = 16;
+pub const SYS_break = 17;
+// 18 is freebsd4 getfsstat
+// 19 is old lseek
+pub const SYS_getpid = 20;
+pub const SYS_mount = 21;
+pub const SYS_unmount = 22;
+pub const SYS_setuid = 23;
+pub const SYS_getuid = 24;
+pub const SYS_geteuid = 25;
+pub const SYS_ptrace = 26;
+pub const SYS_recvmsg = 27;
+pub const SYS_sendmsg = 28;
+pub const SYS_recvfrom = 29;
+pub const SYS_accept = 30;
+pub const SYS_getpeername = 31;
+pub const SYS_getsockname = 32;
+pub const SYS_access = 33;
+pub const SYS_chflags = 34;
+pub const SYS_fchflags = 35;
+pub const SYS_sync = 36;
+pub const SYS_kill = 37;
+// 38 is old stat
+pub const SYS_getppid = 39;
+// 40 is old lstat
+pub const SYS_dup = 41;
+pub const SYS_freebsd10_pipe = 42;
+pub const SYS_getegid = 43;
+pub const SYS_profil = 44;
+pub const SYS_ktrace = 45;
+// 46 is old sigaction
+pub const SYS_getgid = 47;
+// 48 is old sigprocmask
+pub const SYS_getlogin = 49;
+pub const SYS_setlogin = 50;
+pub const SYS_acct = 51;
+// 52 is old sigpending
+pub const SYS_sigaltstack = 53;
+pub const SYS_ioctl = 54;
+pub const SYS_reboot = 55;
+pub const SYS_revoke = 56;
+pub const SYS_symlink = 57;
+pub const SYS_readlink = 58;
+pub const SYS_execve = 59;
+pub const SYS_umask = 60;
+pub const SYS_chroot = 61;
+// 62 is old fstat
+// 63 is old getkerninfo
+// 64 is old getpagesize
+pub const SYS_msync = 65;
+pub const SYS_vfork = 66;
+// 67 is obsolete vread
+// 68 is obsolete vwrite
+// 69 is obsolete sbrk (still present on some platforms)
+pub const SYS_sstk = 70;
+// 71 is old mmap
+pub const SYS_vadvise = 72;
+pub const SYS_munmap = 73;
+pub const SYS_mprotect = 74;
+pub const SYS_madvise = 75;
+// 76 is obsolete vhangup
+// 77 is obsolete vlimit
+pub const SYS_mincore = 78;
+pub const SYS_getgroups = 79;
+pub const SYS_setgroups = 80;
+pub const SYS_getpgrp = 81;
+pub const SYS_setpgid = 82;
+pub const SYS_setitimer = 83;
+// 84 is old wait
+pub const SYS_swapon = 85;
+pub const SYS_getitimer = 86;
+// 87 is old gethostname
+// 88 is old sethostname
+pub const SYS_getdtablesize = 89;
+pub const SYS_dup2 = 90;
+pub const SYS_fcntl = 92;
+pub const SYS_select = 93;
+pub const SYS_fsync = 95;
+pub const SYS_setpriority = 96;
+pub const SYS_socket = 97;
+pub const SYS_connect = 98;
+// 99 is old accept
+pub const SYS_getpriority = 100;
+// 101 is old send
+// 102 is old recv
+// 103 is old sigreturn
+pub const SYS_bind = 104;
+pub const SYS_setsockopt = 105;
+pub const SYS_listen = 106;
+// 107 is obsolete vtimes
+// 108 is old sigvec
+// 109 is old sigblock
+// 110 is old sigsetmask
+// 111 is old sigsuspend
+// 112 is old sigstack
+// 113 is old recvmsg
+// 114 is old sendmsg
+// 115 is obsolete vtrace
+pub const SYS_gettimeofday = 116;
+pub const SYS_getrusage = 117;
+pub const SYS_getsockopt = 118;
+pub const SYS_readv = 120;
+pub const SYS_writev = 121;
+pub const SYS_settimeofday = 122;
+pub const SYS_fchown = 123;
+pub const SYS_fchmod = 124;
+// 125 is old recvfrom
+pub const SYS_setreuid = 126;
+pub const SYS_setregid = 127;
+pub const SYS_rename = 128;
+// 129 is old truncate
+// 130 is old ftruncate
+pub const SYS_flock = 131;
+pub const SYS_mkfifo = 132;
+pub const SYS_sendto = 133;
+pub const SYS_shutdown = 134;
+pub const SYS_socketpair = 135;
+pub const SYS_mkdir = 136;
+pub const SYS_rmdir = 137;
+pub const SYS_utimes = 138;
+// 139 is obsolete 4.2 sigreturn
+pub const SYS_adjtime = 140;
+// 141 is old getpeername
+// 142 is old gethostid
+// 143 is old sethostid
+// 144 is old getrlimit
+// 145 is old setrlimit
+// 146 is old killpg
+pub const SYS_setsid = 147;
+pub const SYS_quotactl = 148;
+// 149 is old quota
+// 150 is old getsockname
+pub const SYS_nlm_syscall = 154;
+pub const SYS_nfssvc = 155;
+// 156 is old getdirentries
+// 157 is freebsd4 statfs
+// 158 is freebsd4 fstatfs
+pub const SYS_lgetfh = 160;
+pub const SYS_getfh = 161;
+// 162 is freebsd4 getdomainname
+// 163 is freebsd4 setdomainname
+// 164 is freebsd4 uname
+pub const SYS_sysarch = 165;
+pub const SYS_rtprio = 166;
+pub const SYS_semsys = 169;
+pub const SYS_msgsys = 170;
+pub const SYS_shmsys = 171;
+// 173 is freebsd6 pread
+// 174 is freebsd6 pwrite
+pub const SYS_setfib = 175;
+pub const SYS_ntp_adjtime = 176;
+pub const SYS_setgid = 181;
+pub const SYS_setegid = 182;
+pub const SYS_seteuid = 183;
+// 184 is obsolete lfs_bmapv
+// 185 is obsolete lfs_markv
+// 186 is obsolete lfs_segclean
+// 187 is obsolete lfs_segwait
+pub const SYS_freebsd11_stat = 188;
+pub const SYS_freebsd11_fstat = 189;
+pub const SYS_freebsd11_lstat = 190;
+pub const SYS_pathconf = 191;
+pub const SYS_fpathconf = 192;
+pub const SYS_getrlimit = 194;
+pub const SYS_setrlimit = 195;
+pub const SYS_freebsd11_getdirentries = 196;
+// 197 is freebsd6 mmap
+pub const SYS___syscall = 198;
+// 199 is freebsd6 lseek
+// 200 is freebsd6 truncate
+// 201 is freebsd6 ftruncate
+pub const SYS___sysctl = 202;
+pub const SYS_mlock = 203;
+pub const SYS_munlock = 204;
+pub const SYS_undelete = 205;
+pub const SYS_futimes = 206;
+pub const SYS_getpgid = 207;
+pub const SYS_poll = 209;
+pub const SYS_freebsd7___semctl = 220;
+pub const SYS_semget = 221;
+pub const SYS_semop = 222;
+pub const SYS_freebsd7_msgctl = 224;
+pub const SYS_msgget = 225;
+pub const SYS_msgsnd = 226;
+pub const SYS_msgrcv = 227;
+pub const SYS_shmat = 228;
+pub const SYS_freebsd7_shmctl = 229;
+pub const SYS_shmdt = 230;
+pub const SYS_shmget = 231;
+pub const SYS_clock_gettime = 232;
+pub const SYS_clock_settime = 233;
+pub const SYS_clock_getres = 234;
+pub const SYS_ktimer_create = 235;
+pub const SYS_ktimer_delete = 236;
+pub const SYS_ktimer_settime = 237;
+pub const SYS_ktimer_gettime = 238;
+pub const SYS_ktimer_getoverrun = 239;
+pub const SYS_nanosleep = 240;
+pub const SYS_ffclock_getcounter = 241;
+pub const SYS_ffclock_setestimate = 242;
+pub const SYS_ffclock_getestimate = 243;
+pub const SYS_clock_nanosleep = 244;
+pub const SYS_clock_getcpuclockid2 = 247;
+pub const SYS_ntp_gettime = 248;
+pub const SYS_minherit = 250;
+pub const SYS_rfork = 251;
+// 252 is obsolete openbsd_poll
+pub const SYS_issetugid = 253;
+pub const SYS_lchown = 254;
+pub const SYS_aio_read = 255;
+pub const SYS_aio_write = 256;
+pub const SYS_lio_listio = 257;
+pub const SYS_freebsd11_getdents = 272;
+pub const SYS_lchmod = 274;
+// 275 is obsolete netbsd_lchown
+pub const SYS_lutimes = 276;
+// 277 is obsolete netbsd_msync
+pub const SYS_freebsd11_nstat = 278;
+pub const SYS_freebsd11_nfstat = 279;
+pub const SYS_freebsd11_nlstat = 280;
+pub const SYS_preadv = 289;
+pub const SYS_pwritev = 290;
+// 297 is freebsd4 fhstatfs
+pub const SYS_fhopen = 298;
+pub const SYS_freebsd11_fhstat = 299;
+pub const SYS_modnext = 300;
+pub const SYS_modstat = 301;
+pub const SYS_modfnext = 302;
+pub const SYS_modfind = 303;
+pub const SYS_kldload = 304;
+pub const SYS_kldunload = 305;
+pub const SYS_kldfind = 306;
+pub const SYS_kldnext = 307;
+pub const SYS_kldstat = 308;
+pub const SYS_kldfirstmod = 309;
+pub const SYS_getsid = 310;
+pub const SYS_setresuid = 311;
+pub const SYS_setresgid = 312;
+// 313 is obsolete signanosleep
+pub const SYS_aio_return = 314;
+pub const SYS_aio_suspend = 315;
+pub const SYS_aio_cancel = 316;
+pub const SYS_aio_error = 317;
+// 318 is freebsd6 aio_read
+// 319 is freebsd6 aio_write
+// 320 is freebsd6 lio_listio
+pub const SYS_yield = 321;
+// 322 is obsolete thr_sleep
+// 323 is obsolete thr_wakeup
+pub const SYS_mlockall = 324;
+pub const SYS_munlockall = 325;
+pub const SYS___getcwd = 326;
+pub const SYS_sched_setparam = 327;
+pub const SYS_sched_getparam = 328;
+pub const SYS_sched_setscheduler = 329;
+pub const SYS_sched_getscheduler = 330;
+pub const SYS_sched_yield = 331;
+pub const SYS_sched_get_priority_max = 332;
+pub const SYS_sched_get_priority_min = 333;
+pub const SYS_sched_rr_get_interval = 334;
+pub const SYS_utrace = 335;
+// 336 is freebsd4 sendfile
+pub const SYS_kldsym = 337;
+pub const SYS_jail = 338;
+pub const SYS_nnpfs_syscall = 339;
+pub const SYS_sigprocmask = 340;
+pub const SYS_sigsuspend = 341;
+// 342 is freebsd4 sigaction
+pub const SYS_sigpending = 343;
+// 344 is freebsd4 sigreturn
+pub const SYS_sigtimedwait = 345;
+pub const SYS_sigwaitinfo = 346;
+pub const SYS___acl_get_file = 347;
+pub const SYS___acl_set_file = 348;
+pub const SYS___acl_get_fd = 349;
+pub const SYS___acl_set_fd = 350;
+pub const SYS___acl_delete_file = 351;
+pub const SYS___acl_delete_fd = 352;
+pub const SYS___acl_aclcheck_file = 353;
+pub const SYS___acl_aclcheck_fd = 354;
+pub const SYS_extattrctl = 355;
+pub const SYS_extattr_set_file = 356;
+pub const SYS_extattr_get_file = 357;
+pub const SYS_extattr_delete_file = 358;
+pub const SYS_aio_waitcomplete = 359;
+pub const SYS_getresuid = 360;
+pub const SYS_getresgid = 361;
+pub const SYS_kqueue = 362;
+pub const SYS_freebsd11_kevent = 363;
+// 364 is obsolete __cap_get_proc
+// 365 is obsolete __cap_set_proc
+// 366 is obsolete __cap_get_fd
+// 367 is obsolete __cap_get_file
+// 368 is obsolete __cap_set_fd
+// 369 is obsolete __cap_set_file
+pub const SYS_extattr_set_fd = 371;
+pub const SYS_extattr_get_fd = 372;
+pub const SYS_extattr_delete_fd = 373;
+pub const SYS___setugid = 374;
+pub const SYS_eaccess = 376;
+pub const SYS_afs3_syscall = 377;
+pub const SYS_nmount = 378;
+// 379 is obsolete kse_exit
+// 380 is obsolete kse_wakeup
+// 381 is obsolete kse_create
+// 382 is obsolete kse_thr_interrupt
+// 383 is obsolete kse_release
+pub const SYS___mac_get_proc = 384;
+pub const SYS___mac_set_proc = 385;
+pub const SYS___mac_get_fd = 386;
+pub const SYS___mac_get_file = 387;
+pub const SYS___mac_set_fd = 388;
+pub const SYS___mac_set_file = 389;
+pub const SYS_kenv = 390;
+pub const SYS_lchflags = 391;
+pub const SYS_uuidgen = 392;
+pub const SYS_sendfile = 393;
+pub const SYS_mac_syscall = 394;
+pub const SYS_freebsd11_getfsstat = 395;
+pub const SYS_freebsd11_statfs = 396;
+pub const SYS_freebsd11_fstatfs = 397;
+pub const SYS_freebsd11_fhstatfs = 398;
+pub const SYS_ksem_close = 400;
+pub const SYS_ksem_post = 401;
+pub const SYS_ksem_wait = 402;
+pub const SYS_ksem_trywait = 403;
+pub const SYS_ksem_init = 404;
+pub const SYS_ksem_open = 405;
+pub const SYS_ksem_unlink = 406;
+pub const SYS_ksem_getvalue = 407;
+pub const SYS_ksem_destroy = 408;
+pub const SYS___mac_get_pid = 409;
+pub const SYS___mac_get_link = 410;
+pub const SYS___mac_set_link = 411;
+pub const SYS_extattr_set_link = 412;
+pub const SYS_extattr_get_link = 413;
+pub const SYS_extattr_delete_link = 414;
+pub const SYS___mac_execve = 415;
+pub const SYS_sigaction = 416;
+pub const SYS_sigreturn = 417;
+pub const SYS_getcontext = 421;
+pub const SYS_setcontext = 422;
+pub const SYS_swapcontext = 423;
+pub const SYS_swapoff = 424;
+pub const SYS___acl_get_link = 425;
+pub const SYS___acl_set_link = 426;
+pub const SYS___acl_delete_link = 427;
+pub const SYS___acl_aclcheck_link = 428;
+pub const SYS_sigwait = 429;
+pub const SYS_thr_create = 430;
+pub const SYS_thr_exit = 431;
+pub const SYS_thr_self = 432;
+pub const SYS_thr_kill = 433;
+pub const SYS_jail_attach = 436;
+pub const SYS_extattr_list_fd = 437;
+pub const SYS_extattr_list_file = 438;
+pub const SYS_extattr_list_link = 439;
+// 440 is obsolete kse_switchin
+pub const SYS_ksem_timedwait = 441;
+pub const SYS_thr_suspend = 442;
+pub const SYS_thr_wake = 443;
+pub const SYS_kldunloadf = 444;
+pub const SYS_audit = 445;
+pub const SYS_auditon = 446;
+pub const SYS_getauid = 447;
+pub const SYS_setauid = 448;
+pub const SYS_getaudit = 449;
+pub const SYS_setaudit = 450;
+pub const SYS_getaudit_addr = 451;
+pub const SYS_setaudit_addr = 452;
+pub const SYS_auditctl = 453;
+pub const SYS__umtx_op = 454;
+pub const SYS_thr_new = 455;
+pub const SYS_sigqueue = 456;
+pub const SYS_kmq_open = 457;
+pub const SYS_kmq_setattr = 458;
+pub const SYS_kmq_timedreceive = 459;
+pub const SYS_kmq_timedsend = 460;
+pub const SYS_kmq_notify = 461;
+pub const SYS_kmq_unlink = 462;
+pub const SYS_abort2 = 463;
+pub const SYS_thr_set_name = 464;
+pub const SYS_aio_fsync = 465;
+pub const SYS_rtprio_thread = 466;
+pub const SYS_sctp_peeloff = 471;
+pub const SYS_sctp_generic_sendmsg = 472;
+pub const SYS_sctp_generic_sendmsg_iov = 473;
+pub const SYS_sctp_generic_recvmsg = 474;
+pub const SYS_pread = 475;
+pub const SYS_pwrite = 476;
+pub const SYS_mmap = 477;
+pub const SYS_lseek = 478;
+pub const SYS_truncate = 479;
+pub const SYS_ftruncate = 480;
+pub const SYS_thr_kill2 = 481;
+pub const SYS_shm_open = 482;
+pub const SYS_shm_unlink = 483;
+pub const SYS_cpuset = 484;
+pub const SYS_cpuset_setid = 485;
+pub const SYS_cpuset_getid = 486;
+pub const SYS_cpuset_getaffinity = 487;
+pub const SYS_cpuset_setaffinity = 488;
+pub const SYS_faccessat = 489;
+pub const SYS_fchmodat = 490;
+pub const SYS_fchownat = 491;
+pub const SYS_fexecve = 492;
+pub const SYS_freebsd11_fstatat = 493;
+pub const SYS_futimesat = 494;
+pub const SYS_linkat = 495;
+pub const SYS_mkdirat = 496;
+pub const SYS_mkfifoat = 497;
+pub const SYS_freebsd11_mknodat = 498;
+pub const SYS_openat = 499;
+pub const SYS_readlinkat = 500;
+pub const SYS_renameat = 501;
+pub const SYS_symlinkat = 502;
+pub const SYS_unlinkat = 503;
+pub const SYS_posix_openpt = 504;
+pub const SYS_gssd_syscall = 505;
+pub const SYS_jail_get = 506;
+pub const SYS_jail_set = 507;
+pub const SYS_jail_remove = 508;
+pub const SYS_closefrom = 509;
+pub const SYS___semctl = 510;
+pub const SYS_msgctl = 511;
+pub const SYS_shmctl = 512;
+pub const SYS_lpathconf = 513;
+// 514 is obsolete cap_new
+pub const SYS___cap_rights_get = 515;
+pub const SYS_cap_enter = 516;
+pub const SYS_cap_getmode = 517;
+pub const SYS_pdfork = 518;
+pub const SYS_pdkill = 519;
+pub const SYS_pdgetpid = 520;
+pub const SYS_pselect = 522;
+pub const SYS_getloginclass = 523;
+pub const SYS_setloginclass = 524;
+pub const SYS_rctl_get_racct = 525;
+pub const SYS_rctl_get_rules = 526;
+pub const SYS_rctl_get_limits = 527;
+pub const SYS_rctl_add_rule = 528;
+pub const SYS_rctl_remove_rule = 529;
+pub const SYS_posix_fallocate = 530;
+pub const SYS_posix_fadvise = 531;
+pub const SYS_wait6 = 532;
+pub const SYS_cap_rights_limit = 533;
+pub const SYS_cap_ioctls_limit = 534;
+pub const SYS_cap_ioctls_get = 535;
+pub const SYS_cap_fcntls_limit = 536;
+pub const SYS_cap_fcntls_get = 537;
+pub const SYS_bindat = 538;
+pub const SYS_connectat = 539;
+pub const SYS_chflagsat = 540;
+pub const SYS_accept4 = 541;
+pub const SYS_pipe2 = 542;
+pub const SYS_aio_mlock = 543;
+pub const SYS_procctl = 544;
+pub const SYS_ppoll = 545;
+pub const SYS_futimens = 546;
+pub const SYS_utimensat = 547;
+// 548 is obsolete numa_getaffinity
+// 549 is obsolete numa_setaffinity
+pub const SYS_fdatasync = 550;
+pub const SYS_fstat = 551;
+pub const SYS_fstatat = 552;
+pub const SYS_fhstat = 553;
+pub const SYS_getdirentries = 554;
+pub const SYS_statfs = 555;
+pub const SYS_fstatfs = 556;
+pub const SYS_getfsstat = 557;
+pub const SYS_fhstatfs = 558;
+pub const SYS_mknodat = 559;
+pub const SYS_kevent = 560;
+pub const SYS_cpuset_getdomain = 561;
+pub const SYS_cpuset_setdomain = 562;
+pub const SYS_getrandom = 563;
+pub const SYS_MAXSYSCALL = 564;
diff --git a/std/os/freebsd/x86_64.zig b/std/os/freebsd/x86_64.zig
new file mode 100644
index 0000000000..28ae2d5471
--- /dev/null
+++ b/std/os/freebsd/x86_64.zig
@@ -0,0 +1,136 @@
+const freebsd = @import("index.zig");
+const socklen_t = freebsd.socklen_t;
+const iovec = freebsd.iovec;
+
+pub const SYS_sbrk = 69;
+
+pub fn syscall0(number: usize) usize {
+    return asm volatile ("syscall"
+        : [ret] "={rax}" (-> usize)
+        : [number] "{rax}" (number)
+        : "rcx", "r11"
+    );
+}
+
+pub fn syscall1(number: usize, arg1: usize) usize {
+    return asm volatile ("syscall"
+        : [ret] "={rax}" (-> usize)
+        : [number] "{rax}" (number),
+          [arg1] "{rdi}" (arg1)
+        : "rcx", "r11"
+    );
+}
+
+pub fn syscall2(number: usize, arg1: usize, arg2: usize) usize {
+    return asm volatile ("syscall"
+        : [ret] "={rax}" (-> usize)
+        : [number] "{rax}" (number),
+          [arg1] "{rdi}" (arg1),
+          [arg2] "{rsi}" (arg2)
+        : "rcx", "r11"
+    );
+}
+
+pub fn syscall3(number: usize, arg1: usize, arg2: usize, arg3: usize) usize {
+    return asm volatile ("syscall"
+        : [ret] "={rax}" (-> usize)
+        : [number] "{rax}" (number),
+          [arg1] "{rdi}" (arg1),
+          [arg2] "{rsi}" (arg2),
+          [arg3] "{rdx}" (arg3)
+        : "rcx", "r11"
+    );
+}
+
+pub fn syscall4(number: usize, arg1: usize, arg2: usize, arg3: usize, arg4: usize) usize {
+    return asm volatile ("syscall"
+        : [ret] "={rax}" (-> usize)
+        : [number] "{rax}" (number),
+          [arg1] "{rdi}" (arg1),
+          [arg2] "{rsi}" (arg2),
+          [arg3] "{rdx}" (arg3),
+          [arg4] "{r10}" (arg4)
+        : "rcx", "r11"
+    );
+}
+
+pub fn syscall5(number: usize, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) usize {
+    return asm volatile ("syscall"
+        : [ret] "={rax}" (-> usize)
+        : [number] "{rax}" (number),
+          [arg1] "{rdi}" (arg1),
+          [arg2] "{rsi}" (arg2),
+          [arg3] "{rdx}" (arg3),
+          [arg4] "{r10}" (arg4),
+          [arg5] "{r8}" (arg5)
+        : "rcx", "r11"
+    );
+}
+
+pub fn syscall6(
+    number: usize,
+    arg1: usize,
+    arg2: usize,
+    arg3: usize,
+    arg4: usize,
+    arg5: usize,
+    arg6: usize,
+) usize {
+    return asm volatile ("syscall"
+        : [ret] "={rax}" (-> usize)
+        : [number] "{rax}" (number),
+          [arg1] "{rdi}" (arg1),
+          [arg2] "{rsi}" (arg2),
+          [arg3] "{rdx}" (arg3),
+          [arg4] "{r10}" (arg4),
+          [arg5] "{r8}" (arg5),
+          [arg6] "{r9}" (arg6)
+        : "rcx", "r11"
+    );
+}
+
+pub nakedcc fn restore_rt() void {
+    asm volatile ("syscall"
+        :
+        : [number] "{rax}" (usize(SYS_rt_sigreturn))
+        : "rcx", "r11"
+    );
+}
+
+pub const msghdr = extern struct.{
+    msg_name: &u8,
+    msg_namelen: socklen_t,
+    msg_iov: &iovec,
+    msg_iovlen: i32,
+    __pad1: i32,
+    msg_control: &u8,
+    msg_controllen: socklen_t,
+    __pad2: socklen_t,
+    msg_flags: i32,
+};
+
+/// Renamed to Stat to not conflict with the stat function.
+pub const Stat = extern struct.{
+    dev: u64,
+    ino: u64,
+    nlink: usize,
+
+    mode: u32,
+    uid: u32,
+    gid: u32,
+    __pad0: u32,
+    rdev: u64,
+    size: i64,
+    blksize: isize,
+    blocks: i64,
+
+    atim: timespec,
+    mtim: timespec,
+    ctim: timespec,
+    __unused: [3]isize,
+};
+
+pub const timespec = extern struct.{
+    tv_sec: isize,
+    tv_nsec: isize,
+};
diff --git a/std/os/get_app_data_dir.zig b/std/os/get_app_data_dir.zig
index da9c6c3cb4..ae133bb4b1 100644
--- a/std/os/get_app_data_dir.zig
+++ b/std/os/get_app_data_dir.zig
@@ -43,7 +43,7 @@ pub fn getAppDataDir(allocator: *mem.Allocator, appname: []const u8) GetAppDataD
             };
             return os.path.join(allocator, home_dir, "Library", "Application Support", appname);
         },
-        builtin.Os.linux => {
+        builtin.Os.linux, builtin.Os.freebsd => {
             const home_dir = os.getEnvPosix("HOME") orelse {
                 // TODO look in /etc/passwd
                 return error.AppDataDirUnavailable;
diff --git a/std/os/get_user_id.zig b/std/os/get_user_id.zig
index c0c1b1cc4b..9a4d1ab275 100644
--- a/std/os/get_user_id.zig
+++ b/std/os/get_user_id.zig
@@ -11,7 +11,7 @@ pub const UserInfo = struct {
 /// POSIX function which gets a uid from username.
 pub fn getUserInfo(name: []const u8) !UserInfo {
     return switch (builtin.os) {
-        Os.linux, Os.macosx, Os.ios => posixGetUserInfo(name),
+        Os.linux, Os.macosx, Os.ios, Os.freebsd => posixGetUserInfo(name),
         else => @compileError("Unsupported OS"),
     };
 }
diff --git a/std/os/index.zig b/std/os/index.zig
index e1915a2012..ba1fdb2be6 100644
--- a/std/os/index.zig
+++ b/std/os/index.zig
@@ -3,7 +3,7 @@ const builtin = @import("builtin");
 const Os = builtin.Os;
 const is_windows = builtin.os == Os.windows;
 const is_posix = switch (builtin.os) {
-    builtin.Os.linux, builtin.Os.macosx => true,
+    builtin.Os.linux, builtin.Os.macosx, builtin.Os.freebsd => true,
     else => false,
 };
 const os = @This();
@@ -24,10 +24,12 @@ test "std.os" {
 pub const windows = @import("windows/index.zig");
 pub const darwin = @import("darwin.zig");
 pub const linux = @import("linux/index.zig");
+pub const freebsd = @import("freebsd/index.zig");
 pub const zen = @import("zen.zig");
 pub const posix = switch (builtin.os) {
     Os.linux => linux,
     Os.macosx, Os.ios => darwin,
+    Os.freebsd => freebsd,
     Os.zen => zen,
     else => @compileError("Unsupported OS"),
 };
@@ -40,7 +42,7 @@ pub const time = @import("time.zig");
 
 pub const page_size = 4 * 1024;
 pub const MAX_PATH_BYTES = switch (builtin.os) {
-    Os.linux, Os.macosx, Os.ios => posix.PATH_MAX,
+    Os.linux, Os.macosx, Os.ios, Os.freebsd => posix.PATH_MAX,
     // Each UTF-16LE character may be expanded to 3 UTF-8 bytes.
     // If it would require 4 UTF-8 bytes, then there would be a surrogate
     // pair in the UTF-16LE, and we (over)account 3 bytes for it that way.
@@ -101,7 +103,7 @@ const math = std.math;
 /// library implementation.
 pub fn getRandomBytes(buf: []u8) !void {
     switch (builtin.os) {
-        Os.linux => while (true) {
+        Os.linux, Os.freebsd => while (true) {
             // TODO check libc version and potentially call c.getrandom.
             // See #397
             const errno = posix.getErrno(posix.getrandom(buf.ptr, buf.len, 0));
@@ -174,7 +176,7 @@ pub fn abort() noreturn {
         c.abort();
     }
     switch (builtin.os) {
-        Os.linux, Os.macosx, Os.ios => {
+        Os.linux, Os.macosx, Os.ios, Os.freebsd => {
             _ = posix.raise(posix.SIGABRT);
             _ = posix.raise(posix.SIGKILL);
             while (true) {}
@@ -196,7 +198,7 @@ pub fn exit(status: u8) noreturn {
         c.exit(status);
     }
     switch (builtin.os) {
-        Os.linux, Os.macosx, Os.ios => {
+        Os.linux, Os.macosx, Os.ios, Os.freebsd => {
             posix.exit(status);
         },
         Os.windows => {
@@ -419,7 +421,7 @@ pub fn posix_pwritev(fd: i32, iov: [*]const posix.iovec_const, count: usize, off
                 }
             }
         },
-        builtin.Os.linux => while (true) {
+        builtin.Os.linux, builtin.Os.freebsd => while (true) {
             const rc = posix.pwritev(fd, iov, count, offset);
             const err = posix.getErrno(rc);
             switch (err) {
@@ -687,7 +689,7 @@ pub fn getBaseAddress() usize {
             };
             return phdr - @sizeOf(ElfHeader);
         },
-        builtin.Os.macosx => return @ptrToInt(&std.c._mh_execute_header),
+        builtin.Os.macosx, builtin.Os.freebsd => return @ptrToInt(&std.c._mh_execute_header),
         builtin.Os.windows => return @ptrToInt(windows.GetModuleHandleW(null)),
         else => @compileError("Unsupported OS"),
     }
@@ -1305,7 +1307,7 @@ pub fn deleteDirC(dir_path: [*]const u8) DeleteDirError!void {
             const dir_path_w = try windows_util.cStrToPrefixedFileW(dir_path);
             return deleteDirW(&dir_path_w);
         },
-        Os.linux, Os.macosx, Os.ios => {
+        Os.linux, Os.macosx, Os.ios, Os.freebsd => {
             const err = posix.getErrno(posix.rmdir(dir_path));
             switch (err) {
                 0 => return,
@@ -1348,7 +1350,7 @@ pub fn deleteDir(dir_path: []const u8) DeleteDirError!void {
             const dir_path_w = try windows_util.sliceToPrefixedFileW(dir_path);
             return deleteDirW(&dir_path_w);
         },
-        Os.linux, Os.macosx, Os.ios => {
+        Os.linux, Os.macosx, Os.ios, Os.freebsd => {
             const dir_path_c = try toPosixPath(dir_path);
             return deleteDirC(&dir_path_c);
         },
@@ -1465,7 +1467,7 @@ pub const Dir = struct {
     allocator: *Allocator,
 
     pub const Handle = switch (builtin.os) {
-        Os.macosx, Os.ios => struct {
+        Os.macosx, Os.ios, Os.freebsd => struct {
             fd: i32,
             seek: i64,
             buf: []u8,
@@ -1541,7 +1543,7 @@ pub const Dir = struct {
                         .name_data = undefined,
                     };
                 },
-                Os.macosx, Os.ios => Handle{
+                Os.macosx, Os.ios, Os.freebsd => Handle{
                     .fd = try posixOpen(
                         dir_path,
                         posix.O_RDONLY | posix.O_NONBLOCK | posix.O_DIRECTORY | posix.O_CLOEXEC,
@@ -1572,7 +1574,7 @@ pub const Dir = struct {
             Os.windows => {
                 _ = windows.FindClose(self.handle.handle);
             },
-            Os.macosx, Os.ios, Os.linux => {
+            Os.macosx, Os.ios, Os.linux, Os.freebsd => {
                 self.allocator.free(self.handle.buf);
                 os.close(self.handle.fd);
             },
@@ -1587,6 +1589,7 @@ pub const Dir = struct {
             Os.linux => return self.nextLinux(),
             Os.macosx, Os.ios => return self.nextDarwin(),
             Os.windows => return self.nextWindows(),
+            Os.freebsd => return self.nextFreebsd(),
             else => @compileError("unimplemented"),
         }
     }
@@ -1726,6 +1729,11 @@ pub const Dir = struct {
             };
         }
     }
+
+    fn nextFreebsd(self: *Dir) !?Entry {
+        self.handle.buf = try self.allocator.alloc(u8, page_size);
+        return null; // TODO
+    }
 };
 
 pub fn changeCurDir(allocator: *Allocator, dir_path: []const u8) !void {
@@ -2164,7 +2172,7 @@ pub fn unexpectedErrorWindows(err: windows.DWORD) UnexpectedError {
 pub fn openSelfExe() !os.File {
     switch (builtin.os) {
         Os.linux => return os.File.openReadC(c"/proc/self/exe"),
-        Os.macosx, Os.ios => {
+        Os.macosx, Os.ios, Os.freebsd => {
             var buf: [MAX_PATH_BYTES]u8 = undefined;
             const self_exe_path = try selfExePath(&buf);
             buf[self_exe_path.len] = 0;
@@ -2181,7 +2189,7 @@ pub fn openSelfExe() !os.File {
 
 test "openSelfExe" {
     switch (builtin.os) {
-        Os.linux, Os.macosx, Os.ios, Os.windows => (try openSelfExe()).close(),
+        Os.linux, Os.macosx, Os.ios, Os.windows, Os.freebsd => (try openSelfExe()).close(),
         else => return error.SkipZigTest, // Unsupported OS.
     }
 }
@@ -2212,6 +2220,7 @@ pub fn selfExePathW(out_buffer: *[windows_util.PATH_MAX_WIDE]u16) ![]u16 {
 pub fn selfExePath(out_buffer: *[MAX_PATH_BYTES]u8) ![]u8 {
     switch (builtin.os) {
         Os.linux => return readLink(out_buffer, "/proc/self/exe"),
+        Os.freebsd => return readLink(out_buffer, "/proc/curproc/file"),
         Os.windows => {
             var utf16le_buf: [windows_util.PATH_MAX_WIDE]u16 = undefined;
             const utf16le_slice = try selfExePathW(&utf16le_buf);
@@ -2250,7 +2259,7 @@ pub fn selfExeDirPath(out_buffer: *[MAX_PATH_BYTES]u8) ![]const u8 {
             // will not return null.
             return path.dirname(full_exe_path).?;
         },
-        Os.windows, Os.macosx, Os.ios => {
+        Os.windows, Os.macosx, Os.ios, Os.freebsd => {
             const self_exe_path = try selfExePath(out_buffer);
             // Assume that the OS APIs return absolute paths, and therefore dirname
             // will not return null.
@@ -3095,10 +3104,13 @@ pub const CpuCountError = error{
 
 pub fn cpuCount(fallback_allocator: *mem.Allocator) CpuCountError!usize {
     switch (builtin.os) {
-        builtin.Os.macosx => {
+        builtin.Os.macosx, builtin.Os.freebsd => {
             var count: c_int = undefined;
             var count_len: usize = @sizeOf(c_int);
-            const rc = posix.sysctlbyname(c"hw.logicalcpu", @ptrCast(*c_void, &count), &count_len, null, 0);
+            const rc = posix.sysctlbyname(switch (builtin.os) {
+                builtin.Os.macosx => c"hw.logicalcpu",
+                else => c"hw.ncpu",
+            }, @ptrCast(*c_void, &count), &count_len, null, 0);
             const err = posix.getErrno(rc);
             switch (err) {
                 0 => return @intCast(usize, count),
diff --git a/std/os/path.zig b/std/os/path.zig
index b3cfec1a3a..4ef7f3effb 100644
--- a/std/os/path.zig
+++ b/std/os/path.zig
@@ -1188,6 +1188,15 @@ pub fn realC(out_buffer: *[os.MAX_PATH_BYTES]u8, pathname: [*]const u8) RealErro
 
             return os.readLinkC(out_buffer, proc_path.ptr);
         },
+        Os.freebsd => { // XXX requires fdescfs
+            const fd = try os.posixOpenC(pathname, posix.O_PATH | posix.O_NONBLOCK | posix.O_CLOEXEC, 0);
+            defer os.close(fd);
+
+            var buf: ["/dev/fd/-2147483648".len]u8 = undefined;
+            const proc_path = fmt.bufPrint(buf[0..], "/dev/fd/{}\x00", fd) catch unreachable;
+
+            return os.readLinkC(out_buffer, proc_path.ptr);
+        },
         else => @compileError("TODO implement os.path.real for " ++ @tagName(builtin.os)),
     }
 }
@@ -1202,7 +1211,7 @@ pub fn real(out_buffer: *[os.MAX_PATH_BYTES]u8, pathname: []const u8) RealError!
             const pathname_w = try windows_util.sliceToPrefixedFileW(pathname);
             return realW(out_buffer, &pathname_w);
         },
-        Os.macosx, Os.ios, Os.linux => {
+        Os.macosx, Os.ios, Os.linux, Os.freebsd => {
             const pathname_c = try os.toPosixPath(pathname);
             return realC(out_buffer, &pathname_c);
         },
diff --git a/std/special/bootstrap.zig b/std/special/bootstrap.zig
index 53c646abdc..070a26bf71 100644
--- a/std/special/bootstrap.zig
+++ b/std/special/bootstrap.zig
@@ -20,10 +20,17 @@ comptime {
 
 nakedcc fn _start() noreturn {
     switch (builtin.arch) {
-        builtin.Arch.x86_64 => {
-            argc_ptr = asm ("lea (%%rsp), %[argc]"
-                : [argc] "=r" (-> [*]usize)
-            );
+        builtin.Arch.x86_64 => switch (builtin.os) {
+            builtin.Os.freebsd => {
+                argc_ptr = asm ("lea (%%rdi), %[argc]"
+                     : [argc] "=r" (-> [*]usize)
+                );
+            },
+            else => {
+                argc_ptr = asm ("lea (%%rsp), %[argc]"
+                    : [argc] "=r" (-> [*]usize)
+                );
+            },
         },
         builtin.Arch.i386 => {
             argc_ptr = asm ("lea (%%esp), %[argc]"
@@ -50,6 +57,9 @@ extern fn WinMainCRTStartup() noreturn {
 
 // TODO https://github.com/ziglang/zig/issues/265
 fn posixCallMainAndExit() noreturn {
+    if (builtin.os == builtin.Os.freebsd) {
+        @setAlignStack(16);
+    }
     const argc = argc_ptr[0];
     const argv = @ptrCast([*][*]u8, argc_ptr + 1);