https://bugs.freedesktop.org/show_bug.cgi?id=110214
--- Comment #39 from Michel Dänzer michel@daenzer.net --- (In reply to Diego Viola from comment #38)
Unfortunately that's not the issue, llvm-libs 8.0.0 just landed on Arch Linux [extra] repository and the issue still persists.
Has Mesa been rebuilt against the new LLVM? Check the glxinfo output.