https://bugs.freedesktop.org/show_bug.cgi?id=94037
--- Comment #4 from peter.fiss@gmx.de --- I needed to install llvm-svn, because it was a dependency of mesa-git from the Arch User Repository. As a non-mesa-dev this seemed to be the easiest way for me to get mesa-git to work.
Anyway, I can confirm that the bug is fixed in mesa-git. Thanks for your help and for the excellent response time!