http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54283
--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-08-16 15:29:24 UTC --- Maybe related that we don't build a "host" libstdc++-v3 but only a target one: target_modules = { module= libstdc++-v3; bootstrap=true; lib_path=src/.libs; raw_cxx=true; }; and funnily we bootstrap it. We should bootstrap a host libstdc++-v3 and build a target libstdc++-v3 (if C++ is enabled). The host libstdc++-v3 would not need libstdc++ PCHs or multilibs of course.