https://bugs.freedesktop.org/show_bug.cgi?id=81644
--- Comment #74 from Michel Dänzer michel@daenzer.net --- (In reply to comment #73)
Could it be I'm using LLVM 3.6 [...]
Yes, only released versions of LLVM can be supported by released versions of Mesa. Even LLVM 3.5 is only being released now, so you might need LLVM 3.4(.y) for Mesa 10.1.