https://bugs.freedesktop.org/show_bug.cgi?id=76223
--- Comment #23 from Michel Dänzer michel@daenzer.net ---
(EE) AIGLX error: dlopen of /usr/lib/xorg/modules/dri/swrast_dri.so failed (libLLVM-3.5.so: cannot open shared object file: No such file or directory)
Looks like the dynamic linker can't find libLLVM-3.5.so anymore. Did you run ldconfig after installing LLVM?