Index: configure
===================================================================
--- configure	(revision 198135)
+++ configure	(working copy)
@@ -71877,10 +71877,11 @@ rm -f core conftest.err conftest.$ac_objext confte
 
 fi
 
+
+
   if test $ac_cv_x86_rdrand = yes; then
+    $as_echo "#define _GLIBCXX_X86_RDRAND 1" >>confdefs.h
 
-$as_echo "#define _GLIBCXX_X86_RDRAND 1" >>confdefs.h
-
   fi
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_x86_rdrand" >&5
 $as_echo "$ac_cv_x86_rdrand" >&6; }
Index: acinclude.m4
===================================================================
--- acinclude.m4	(revision 198135)
+++ acinclude.m4	(working copy)
@@ -3484,9 +3484,15 @@ AC_DEFUN([GLIBCXX_CHECK_X86_RDRAND], [
 		[ac_cv_x86_rdrand=yes], [ac_cv_x86_rdrand=no])
   esac
   ])
+  AH_VERBATIM([_GLIBCXX_X86_RDRAND,],
+              [/* Defined if as can handle rdrand.
+   Disable when building with Clang.  Google ref b/8680429 */
+#ifndef __clang__
+#undef _GLIBCXX_X86_RDRAND
+#endif])
+
   if test $ac_cv_x86_rdrand = yes; then
-    AC_DEFINE(_GLIBCXX_X86_RDRAND, 1,
-		[ Defined if as can handle rdrand. ])
+    AC_DEFINE(_GLIBCXX_X86_RDRAND, 1)
   fi
   AC_MSG_RESULT($ac_cv_x86_rdrand)
 ])
Index: config.h.in
===================================================================
--- config.h.in	(revision 198135)
+++ config.h.in	(working copy)
@@ -872,8 +872,11 @@
 /* Define to 1 if a verbose library is built, or 0 otherwise. */
 #undef _GLIBCXX_VERBOSE
 
-/* Defined if as can handle rdrand. */
+/* Defined if as can handle rdrand.
+   Disable when building with Clang.  Google ref b/8680429 */
+#ifndef __clang__
 #undef _GLIBCXX_X86_RDRAND
+#endif
 
 /* Define to 1 if mutex_timedlock is available. */
 #undef _GTHREAD_USE_MUTEX_TIMEDLOCK