--- build/config/BUILDCONFIG.gn.orig	2021-11-15 18:52:18 UTC
+++ build/config/BUILDCONFIG.gn
@@ -136,7 +136,7 @@ declare_args() {
   is_official_build = false
 
   # Set to true when compiling with the Clang compiler.
-  is_clang = current_os != "linux" ||
+  is_clang = current_os != "linux" || current_os == "freebsd" ||
              (current_cpu != "s390x" && current_cpu != "s390" &&
               current_cpu != "ppc64" && current_cpu != "ppc" &&
               current_cpu != "mips" && current_cpu != "mips64" &&
@@ -189,8 +189,8 @@ if (host_toolchain == "") {
   # TODO(dpranke): Add some sort of assert here that verifies that
   # no toolchain omitted host_toolchain from its toolchain_args().
 
-  if (host_os == "linux") {
-    if (target_os != "linux") {
+  if (host_os == "linux" || host_os == "freebsd") {
+    if (target_os != "linux" && target_os != "freebsd") {
       host_toolchain = "//build/toolchain/linux:clang_$host_cpu"
     } else if (is_clang) {
       host_toolchain = "//build/toolchain/linux:clang_$host_cpu"
@@ -229,7 +229,7 @@ if (target_os == "android") {
   assert(host_os == "linux" || host_os == "mac",
          "Android builds are only supported on Linux and Mac hosts.")
   _default_toolchain = "//build/toolchain/android:android_clang_$target_cpu"
-} else if (target_os == "chromeos" || target_os == "linux") {
+} else if (target_os == "chromeos" || target_os == "linux" || target_os == "freebsd") {
   # See comments in build/toolchain/cros/BUILD.gn about board compiles.
   if (is_clang) {
     _default_toolchain = "//build/toolchain/linux:clang_$target_cpu"
@@ -296,10 +296,11 @@ is_android = current_os == "android"
 is_chromeos = current_os == "chromeos"
 is_fuchsia = current_os == "fuchsia"
 is_ios = current_os == "ios"
-is_linux = current_os == "linux"
+is_linux = current_os == "linux" || current_os == "freebsd"
 is_mac = current_os == "mac"
 is_nacl = current_os == "nacl"
 is_win = current_os == "win" || current_os == "winuwp"
+is_bsd = current_os == "freebsd"
 
 is_apple = is_ios || is_mac
 is_posix = !is_win && !is_fuchsia