Seems like you might as well just use one macro, and set it to "target-libstdc++-v3" or "target-libstdc++ target-libio". Configuring with --enable-libstdcxx-v3 should change the default for -fhonor-std, not just how libgcc is built; otherwise, if the user forgets to specify -fhonor-std, her code won't link. Jason