Well, it wasn't searching there! I couldn't quite figure out why, so I went for just adding it explicitly. It could break in the future, particularly if there's a new major release of libc++ that would be in /v2, but for now I'm willing to go with this workaround until we have to cross that bridge. I'd happily accept a better solution, but with only an old 10.6 and a new Mavericks to test on, I had no good way to know and/or verify a better solution and only had so much time to devote to that particular rathole.