Index: llvm/trunk/utils/gn/build/toolchain/BUILD.gn
===================================================================
--- llvm/trunk/utils/gn/build/toolchain/BUILD.gn
+++ llvm/trunk/utils/gn/build/toolchain/BUILD.gn
@@ -150,8 +150,10 @@
   }
 }
 
-if (android_ndk_path != "") {
-  unix_toolchain("stage2_android_aarch64") {
+template("stage2_unix_toolchain") {
+  unix_toolchain(target_name) {
+    forward_variables_from(invoker, "*")
+
     cc = "bin/clang"
     cxx = "bin/clang++"
     ld = cxx
@@ -162,7 +164,19 @@
       "//:lld($host_toolchain)",
       "//:llvm-ar($host_toolchain)",
     ]
+  }
+}
+
+stage2_unix_toolchain("stage2_unix") {
+  toolchain_args = {
+    current_os = host_os
+    current_cpu = host_cpu
+    use_lld = host_os != "mac"
+  }
+}
 
+if (android_ndk_path != "") {
+  stage2_unix_toolchain("stage2_android_aarch64") {
     toolchain_args = {
       current_os = "android"
       current_cpu = "arm64"
Index: llvm/trunk/utils/gn/secondary/BUILD.gn
===================================================================
--- llvm/trunk/utils/gn/secondary/BUILD.gn
+++ llvm/trunk/utils/gn/secondary/BUILD.gn
@@ -9,9 +9,9 @@
     "//llvm/test",
   ]
 
+  # FIXME: This should be a dependency of a test target instead of being
+  # depended on from here.
   if (android_ndk_path != "") {
-    # FIXME: This should be a dependency of a test target instead of being
-    # depended on from here.
     android_aarch64_toolchain =
         "//llvm/utils/gn/build/toolchain:stage2_android_aarch64"
     deps += [
@@ -19,6 +19,9 @@
       "//llvm/tools/llvm-symbolizer($android_aarch64_toolchain)",
     ]
   }
+  if (host_cpu == "x64" && host_os == "linux") {
+    deps += [ "//compiler-rt/lib/hwasan:hwasan_shared(//llvm/utils/gn/build/toolchain:stage2_unix)" ]
+  }
 
   testonly = true
 }
Index: llvm/trunk/utils/gn/secondary/compiler-rt/lib/hwasan/BUILD.gn
===================================================================
--- llvm/trunk/utils/gn/secondary/compiler-rt/lib/hwasan/BUILD.gn
+++ llvm/trunk/utils/gn/secondary/compiler-rt/lib/hwasan/BUILD.gn
@@ -1,10 +1,4 @@
-import("//clang/resource_dir.gni")
-
-# FIXME: Make this support more platforms.
-assert(current_os == "android")
-
-runtime_output_dir = "$clang_resource_dir/lib/linux"
-runtime_target = "aarch64-android"
+import("//compiler-rt/target.gni")
 
 action("version_script") {
   script = "//compiler-rt/lib/sanitizer_common/scripts/gen_dynamic_list.py"
@@ -22,10 +16,11 @@
     "--version-list",
     "--extra",
     rebase_path(sources[0], root_build_dir),
-    rebase_path("$runtime_output_dir/libclang_rt.hwasan-$runtime_target.a",
-                root_build_dir),
-    rebase_path("$runtime_output_dir/libclang_rt.hwasan_cxx-$runtime_target.a",
+    rebase_path("$crt_current_out_dir/libclang_rt.hwasan-$crt_current_target.a",
                 root_build_dir),
+    rebase_path(
+        "$crt_current_out_dir/libclang_rt.hwasan_cxx-$crt_current_target.a",
+        root_build_dir),
     "-o",
     rebase_path(outputs[0], root_build_dir),
   ]
@@ -66,8 +61,8 @@
 }
 
 static_library("hwasan") {
-  output_dir = runtime_output_dir
-  output_name = "clang_rt.hwasan-$runtime_target"
+  output_dir = crt_current_out_dir
+  output_name = "clang_rt.hwasan-$crt_current_target"
   complete_static_lib = true
   configs -= [ "//llvm/utils/gn/build:llvm_code" ]
   configs += [ "//llvm/utils/gn/build:crt_code" ]
@@ -77,8 +72,8 @@
 }
 
 static_library("hwasan_cxx") {
-  output_dir = runtime_output_dir
-  output_name = "clang_rt.hwasan_cxx-$runtime_target"
+  output_dir = crt_current_out_dir
+  output_name = "clang_rt.hwasan_cxx-$crt_current_target"
   complete_static_lib = true
   configs -= [ "//llvm/utils/gn/build:llvm_code" ]
   configs += [ "//llvm/utils/gn/build:crt_code" ]
@@ -88,8 +83,8 @@
 }
 
 shared_library("hwasan_shared") {
-  output_dir = runtime_output_dir
-  output_name = "clang_rt.hwasan-$runtime_target"
+  output_dir = crt_current_out_dir
+  output_name = "clang_rt.hwasan-$crt_current_target"
   configs -= [ "//llvm/utils/gn/build:llvm_code" ]
   configs += [ "//llvm/utils/gn/build:crt_code" ]
   deps = [
Index: llvm/trunk/utils/gn/secondary/compiler-rt/lib/sanitizer_common/BUILD.gn
===================================================================
--- llvm/trunk/utils/gn/secondary/compiler-rt/lib/sanitizer_common/BUILD.gn
+++ llvm/trunk/utils/gn/secondary/compiler-rt/lib/sanitizer_common/BUILD.gn
@@ -1,6 +1,16 @@
 source_set("sources") {
   configs -= [ "//llvm/utils/gn/build:llvm_code" ]
   configs += [ "//llvm/utils/gn/build:crt_code" ]
+  deps = [
+    "//llvm/utils/gn/build/libs/pthread",
+  ]
+  libs = []
+  if (current_os == "linux" || current_os == "android") {
+    libs += [ "dl" ]
+  }
+  if (current_os == "linux") {
+    libs += [ "rt" ]
+  }
   sources = [
     "sancov_flags.cc",
     "sanitizer_allocator.cc",
@@ -67,4 +77,7 @@
     "sanitizer_unwind_win.cc",
     "sanitizer_win.cc",
   ]
+  if (current_cpu == "x64") {
+    sources += [ "sanitizer_linux_x86_64.S" ]
+  }
 }
Index: llvm/trunk/utils/gn/secondary/compiler-rt/target.gni
===================================================================
--- llvm/trunk/utils/gn/secondary/compiler-rt/target.gni
+++ llvm/trunk/utils/gn/secondary/compiler-rt/target.gni
@@ -0,0 +1,20 @@
+import("//clang/resource_dir.gni")
+
+if (current_os == "linux" || current_os == "android") {
+  crt_current_out_dir = "$clang_resource_dir/lib/linux"
+} else {
+  assert(false, "unimplemented current_os " + current_os)
+}
+
+if (current_cpu == "x64") {
+  crt_current_target_arch = "x86_64"
+} else if (current_cpu == "arm64") {
+  crt_current_target_arch = "aarch64"
+} else {
+  assert(false, "unimplemented current_cpu " + current_cpu)
+}
+
+crt_current_target = crt_current_target_arch
+if (current_os == "android") {
+  crt_current_target += "-android"
+}