diff --git a/llvm/utils/gn/secondary/BUILD.gn b/llvm/utils/gn/secondary/BUILD.gn
--- a/llvm/utils/gn/secondary/BUILD.gn
+++ b/llvm/utils/gn/secondary/BUILD.gn
@@ -8,6 +8,7 @@
     "//clang-tools-extra/test",
     "//clang/test",
     "//clang/tools/scan-build",
+    "//compiler-rt",
     "//compiler-rt/include",
     "//compiler-rt/lib/scudo",
     "//lld/test",
diff --git a/llvm/utils/gn/secondary/compiler-rt/BUILD.gn b/llvm/utils/gn/secondary/compiler-rt/BUILD.gn
--- a/llvm/utils/gn/secondary/compiler-rt/BUILD.gn
+++ b/llvm/utils/gn/secondary/compiler-rt/BUILD.gn
@@ -5,7 +5,11 @@
 # In the GN build, compiler-rt is always built by just-built clang and lld.
 # FIXME: For macOS and iOS builds, depend on lib in all needed target arch
 # toolchains and then lipo them together for the final output.
-supported_toolchains = [ "//llvm/utils/gn/build/toolchain:stage2_unix" ]
+if (current_os == "win") {
+  supported_toolchains = [ "//llvm/utils/gn/build/toolchain:win" ]
+} else {
+  supported_toolchains = [ "//llvm/utils/gn/build/toolchain:stage2_unix" ]
+}
 if (android_ndk_path != "") {
   supported_toolchains += [
     "//llvm/utils/gn/build/toolchain:stage2_android_aarch64",
diff --git a/llvm/utils/gn/secondary/compiler-rt/lib/BUILD.gn b/llvm/utils/gn/secondary/compiler-rt/lib/BUILD.gn
--- a/llvm/utils/gn/secondary/compiler-rt/lib/BUILD.gn
+++ b/llvm/utils/gn/secondary/compiler-rt/lib/BUILD.gn
@@ -1,8 +1,10 @@
 group("lib") {
-  deps = [
-    "//compiler-rt/lib/asan",
-    "//compiler-rt/lib/builtins",
-    "//compiler-rt/lib/profile",
-    "//compiler-rt/lib/tsan",
-  ]
+  deps = [ "//compiler-rt/lib/profile" ]
+  if (current_os != "win") {
+    deps += [
+      "//compiler-rt/lib/asan",
+      "//compiler-rt/lib/builtins",
+      "//compiler-rt/lib/tsan",
+    ]
+  }
 }
diff --git a/llvm/utils/gn/secondary/compiler-rt/target.gni b/llvm/utils/gn/secondary/compiler-rt/target.gni
--- a/llvm/utils/gn/secondary/compiler-rt/target.gni
+++ b/llvm/utils/gn/secondary/compiler-rt/target.gni
@@ -28,6 +28,9 @@
   }
 } else if (current_os == "ios" || current_os == "mac") {
   crt_current_out_dir = "$clang_resource_dir/lib/darwin"
+} else if (current_os == "win") {
+  crt_current_out_dir = "$clang_resource_dir/lib/windows"
+  crt_current_target_suffix = "-$crt_current_target_arch"
 } else {
   assert(false, "unimplemented current_os " + current_os)
 }