--- libstdc++-v3/config.h.in.orig	2016-12-12 10:44:08.000000000 -0700
+++ libstdc++-v3/config.h.in	2017-01-14 02:19:10.000000000 -0700
@@ -892,7 +892,9 @@
 #undef _GLIBCXX_USE_FCHMODAT
 
 /* Define if __float128 is supported on this host. */
+#ifndef __clang__
 #undef _GLIBCXX_USE_FLOAT128
+#endif
 
 /* Defined if gettimeofday is available. */
 #undef _GLIBCXX_USE_GETTIMEOFDAY
