Index: libstdc++-v3/src/c++11/random.cc
===================================================================
--- libstdc++-v3/src/c++11/random.cc	(revision 191031)
+++ libstdc++-v3/src/c++11/random.cc	(working copy)
@@ -50,7 +50,7 @@ namespace std _GLIBCXX_VISIBILITY(defaul
       return __ret;
     }
 
-#if defined __i386__ || defined __x86_64__
+#if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
     unsigned int
     __attribute__ ((target("rdrnd")))
     __x86_rdrand(void)
@@ -75,7 +75,7 @@ namespace std _GLIBCXX_VISIBILITY(defaul
 
     if (token == "default")
       {
-#if defined __i386__ || defined __x86_64__
+#if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
 	unsigned int eax, ebx, ecx, edx;
 	// Check availability of cpuid and, for now at least, also the
 	// CPU signature for Intel's
@@ -118,7 +118,7 @@ namespace std _GLIBCXX_VISIBILITY(defaul
   random_device::result_type
   random_device::_M_getval()
   {
-#if (defined __i386__ || defined __x86_64__)
+#if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
     if (! _M_file)
       return __x86_rdrand();
 #endif
Index: libstdc++-v3/configure.ac
===================================================================
--- libstdc++-v3/configure.ac	(revision 191031)
+++ libstdc++-v3/configure.ac	(working copy)
@@ -330,6 +330,18 @@ case "$target" in
 esac
 GLIBCXX_CONDITIONAL(GLIBCXX_LDBL_COMPAT, test $ac_ldbl_compat = yes)
 
+ac_cv_x86_rdrand=no
+case "$target" in
+  i?86-*-* | \
+  x86_64-*-*)
+  AC_TRY_COMPILE(, [asm("rdrand %eax");],
+		 [ac_cv_x86_rdrand=yes], [ac_cv_x86_rdrand=no])
+esac
+if test $ac_cv_x86_rdrand = yes; then
+  AC_DEFINE(_GLIBCXX_X86_RDRAND, 1,
+	    [ Defined if as can handle rdrand. ])
+fi
+
 # This depends on GLIBCXX_ENABLE_SYMVERS and GLIBCXX_IS_NATIVE.
 GLIBCXX_CONFIGURE_TESTSUITE