diff -up chromium-73.0.3683.75/third_party/swiftshader/third_party/llvm-7.0/BUILD.gn.nohh chromium-73.0.3683.75/third_party/swiftshader/third_party/llvm-7.0/BUILD.gn
--- chromium-73.0.3683.75/third_party/swiftshader/third_party/llvm-7.0/BUILD.gn.nohh	2019-03-15 09:02:26.167929864 -0400
+++ chromium-73.0.3683.75/third_party/swiftshader/third_party/llvm-7.0/BUILD.gn	2019-03-15 09:03:30.334433446 -0400
@@ -74,9 +74,12 @@ config("swiftshader_llvm_private_config"
     "-Wno-unused-private-field",
     "-Wno-unused-result",
     "-Wno-unused-variable",
-    "-Wno-error=header-hygiene",
   ]
 
+  if (is_clang) {
+    cflags += [ "-Wno-error=header-hygiene" ]
+  }
+
   defines = [
     "__STDC_CONSTANT_MACROS",
     "__STDC_LIMIT_MACROS",