--- chromium-71.0.3578.98/build/config/compiler/BUILD.gn.orig
+++ chromium-71.0.3578.98/build/config/compiler/BUILD.gn
@@ -236,8 +236,6 @@
 
   configs += [
     # See the definitions below.
-    ":clang_revision",
-    ":compiler_cpu_abi",
     ":compiler_codegen",
   ]
 
@@ -500,17 +498,6 @@
     } else {
       ldflags += [ "-Wl,--color-diagnostics" ]
     }
-  }
-
-  if (is_clang && !is_nacl && !use_xcode_clang) {
-    cflags += [
-      # TODO(hans): Remove this once Clang generates better optimized debug info
-      # by default. https://crbug.com/765793
-      "-Xclang",
-      "-mllvm",
-      "-Xclang",
-      "-instcombine-lower-dbg-declare=0",
-    ]
   }
 
   # Print absolute paths in diagnostics. There is no precedent for doing this
@@ -1499,10 +1486,6 @@
           # TODO(thakis): https://crbug.com/753973
           "-Wno-enum-compare-switch",
 
-          # Ignore warnings about MSVC optimization pragmas.
-          # TODO(thakis): Only for no_chromium_code? http://crbug.com/505314
-          "-Wno-ignored-pragma-optimize",
-
           # TODO(hans): https://crbug.com/890307
           "-Wno-defaulted-function-deleted",
         ]
@@ -1545,22 +1528,6 @@
       "__STDC_CONSTANT_MACROS",
       "__STDC_FORMAT_MACROS",
     ]
-
-    if (!is_debug && !using_sanitizer &&
-        (!is_linux || !is_clang || is_official_build) &&
-        current_cpu != "s390x" && current_cpu != "s390" &&
-        current_cpu != "ppc64" && current_cpu != "ppc64" &&
-        current_cpu != "mips" && current_cpu != "mips64") {
-      # _FORTIFY_SOURCE isn't really supported by Clang now, see
-      # http://llvm.org/bugs/show_bug.cgi?id=16821.
-      # It seems to work fine with Ubuntu 12 headers though, so use it in
-      # official builds.
-      #
-      # Non-chromium code is not guaranteed to compile cleanly with
-      # _FORTIFY_SOURCE. Also, fortified build may fail when optimizations are
-      # disabled, so only do that for Release build.
-      defines += [ "_FORTIFY_SOURCE=2" ]
-    }
 
     if (is_mac) {
       cflags_objc = [ "-Wobjc-missing-property-synthesis" ]