AC_ARG_WITH([clang-libdir],
[AS_HELP_STRING([--with-clang-libdir],
[Path to Clang libraries @<:@default=llvm-config --libdir@:>@])],
[CLANG_LIBDIR="$withval"],
[CLANG_LIBDIR=""])
AC_ARG_WITH([clang-libdir],
[AS_HELP_STRING([--with-clang-libdir],
[Path to Clang libraries @<:@default=llvm-config --libdir@:>@])],
[CLANG_LIBDIR="$withval"],
[CLANG_LIBDIR=""])