Index: gnu/lib/libstdc++/Makefile
===================================================================
--- gnu/lib/libstdc++/Makefile	(revision 255472)
+++ gnu/lib/libstdc++/Makefile	(working copy)
@@ -636,3 +636,7 @@ CLEANFILES+=	${VERSION_MAP}
 
 # Filter out libc++-specific flags, and -std= flags above c++98 or gnu++98.
 CXXFLAGS:=	${CXXFLAGS:N-stdlib=libc++:N-std=c++[01][13x]:N-std=gnu++[01][13x]}
+
+.if ${COMPILER_TYPE} == "clang"
+CXXFLAGS+=	-stdlib=libstdc++
+.endif
Index: gnu/lib/libsupc++/Makefile
===================================================================
--- gnu/lib/libsupc++/Makefile	(revision 255472)
+++ gnu/lib/libsupc++/Makefile	(working copy)
@@ -56,3 +56,7 @@ VERSION_MAP=	${.CURDIR}/Version.map
 
 # Filter out libc++-specific flags, and -std= flags above c++98 or gnu++98.
 CXXFLAGS:=	${CXXFLAGS:N-stdlib=libc++:N-std=c++[01][13x]:N-std=gnu++[01][13x]}
+
+.if ${COMPILER_TYPE} == "clang"
+CXXFLAGS+=	-stdlib=libstdc++
+.endif