--- build/config/compiler/BUILD.gn.orig	2021-07-15 19:13:30 UTC
+++ build/config/compiler/BUILD.gn
@@ -133,7 +133,7 @@ declare_args() {
   #
   # TODO(crbug.com/977230): Enabling this when 'use_xcode_clang' is true may
   # call an old clang that doesn't support auto-init.
-  init_stack_vars = !is_android && !use_xcode_clang
+  init_stack_vars = !is_android && !use_xcode_clang && !is_bsd
 
   # This argument is to control whether enabling text section splitting in the
   # final binary. When enabled, the separated text sections with prefix
@@ -333,7 +333,7 @@ config("compiler") {
     }
 
     # Linker warnings.
-    if (fatal_linker_warnings && !is_apple && current_os != "aix") {
+    if (fatal_linker_warnings && !is_apple && !is_bsd && current_os != "aix") {
       ldflags += [ "-Wl,--fatal-warnings" ]
     }
     if (fatal_linker_warnings && is_apple) {
@@ -428,7 +428,7 @@ config("compiler") {
 
     # Compiler instrumentation can introduce dependencies in DSOs to symbols in
     # the executable they are loaded into, so they are unresolved at link-time.
-    if (!using_sanitizer) {
+    if (!using_sanitizer && !is_bsd) {
       ldflags += [
         "-Wl,-z,defs",
         "-Wl,--as-needed",
@@ -518,7 +518,7 @@ config("compiler") {
     ldflags += [ "-Wl,-z,keep-text-section-prefix" ]
   }
 
-  if (is_clang && !is_nacl && !use_xcode_clang) {
+  if (is_clang && !is_nacl && !use_xcode_clang && !is_bsd) {
     cflags += [ "-fcrash-diagnostics-dir=" + clang_diagnostic_dir ]
 
     # TODO(hans): Remove this once Clang generates better optimized debug info
@@ -661,7 +661,12 @@ config("compiler") {
       # and let it use all cores.
       # TODO(thakis): Check if '=0' (that is, number of cores, instead
       # of "all" which means number of hardware threads) is faster.
-      ldflags += [ "-Wl,--thinlto-jobs=all" ]
+      if (is_bsd) {
+        # FreeBSD < 13 uses LLVM 10, which doesn't support --thinlto-jobs=all
+        ldflags += [ "-Wl,--thinlto-jobs=2" ]
+      } else {
+        ldflags += [ "-Wl,--thinlto-jobs=all" ]
+      }
 
       ldflags += [
         "-Wl,--thinlto-cache-dir=" +
@@ -851,7 +856,7 @@ config("compiler_cpu_abi") {
         cflags += [ "-mtune=$arm_tune" ]
       }
     } else if (current_cpu == "arm64") {
-      if (is_clang && !is_android && !is_nacl && !is_fuchsia) {
+      if (is_clang && !is_android && !is_nacl && !is_fuchsia && !is_bsd) {
         cflags += [ "--target=aarch64-linux-gnu" ]
         ldflags += [ "--target=aarch64-linux-gnu" ]
       }
@@ -1201,7 +1206,7 @@ config("compiler_deterministic") {
       "-Xclang",
       ".",
     ]
-    if (!is_win) {
+    if (!is_win && !is_bsd) {
       # We don't use clang -cc1as on Windows (yet? https://crbug.com/762167)
       asmflags = [ "-Wa,-fdebug-compilation-dir,." ]
     }
@@ -1584,7 +1589,7 @@ config("default_warnings") {
         cflags += [ "-Wno-nonportable-include-path" ]
       }
 
-      if (current_toolchain == host_toolchain || !use_xcode_clang) {
+      if ((current_toolchain == host_toolchain || !use_xcode_clang) && !is_bsd) {
         # Flags NaCl (Clang 3.7) and Xcode 9.2 (Clang clang-900.0.39.2) do not
         # recognize.
         cflags += [
@@ -1625,6 +1630,18 @@ config("default_warnings") {
           cflags += [ "-Wno-max-tokens" ]
         }
       }
+
+      if (is_clang && is_bsd) {
+        cflags += [
+          "-Wno-ignored-pragma-optimize",
+          "-Wno-implicit-int-float-conversion",
+          "-Wno-final-dtor-non-final-class",
+          "-Wno-builtin-assume-aligned-alignment",
+          "-Wno-deprecated-copy",
+          "-Wno-thread-safety-analysis",
+          "-Wno-thread-safety-attributes",
+        ]
+      }
     }
   }
 }
@@ -1754,7 +1771,7 @@ config("no_chromium_code") {
       # suppressing them individually, we just blanket suppress them here.
       "-Wno-unused-variable",
     ]
-    if (!is_nacl && (current_toolchain == host_toolchain || !use_xcode_clang)) {
+    if (!is_nacl && (current_toolchain == host_toolchain || !use_xcode_clang) && !is_bsd) {
       cflags += [
         # TODO(https://crbug.com/1031169): Clean up and enable.
         "-Wno-misleading-indentation",
@@ -1832,7 +1849,7 @@ config("export_dynamic") {
 config("thin_archive") {
   # The macOS and iOS default linker ld64 does not support reading thin
   # archives.
-  if ((is_posix && !is_nacl && (!is_apple || use_lld)) || is_fuchsia) {
+  if ((is_posix && !is_nacl && (!is_apple || use_lld) && !is_bsd) || is_fuchsia) {
     arflags = [ "-T" ]
   } else if (is_win && use_lld) {
     arflags = [ "/llvmlibthin" ]
@@ -2373,7 +2390,7 @@ config("symbols") {
     # flag, so we can use use -g1 for pnacl and nacl-clang compiles.
     # gcc nacl is is_nacl && !is_clang, pnacl and nacl-clang are && is_clang.
     if (!is_nacl || is_clang) {
-      cflags += [ "-g2" ]
+      cflags += [ "-g0" ]
     }
 
     # TODO(https://crbug.com/1050118): Investigate missing debug info on mac.
@@ -2406,7 +2423,7 @@ config("symbols") {
     # DWARF info may be corrupt; offsets in a range list entry are in different
     # sections" there.  Maybe just a bug in nacl_switch_32.S.
     if (!is_apple && !is_nacl && current_cpu != "x86" &&
-        (use_gold || use_lld)) {
+        (use_gold || use_lld) && !is_bsd) {
       if (is_clang) {
         # This flag enables the GNU-format pubnames and pubtypes sections,
         # which lld needs in order to generate a correct GDB index.