https://bugs.freedesktop.org/show_bug.cgi?id=80419
--- Comment #1 from Michel Dänzer michel@daenzer.net --- Please attach /var/log/Xorg.0.log and the output of dmesg and glxinfo.
AMD HD7770 2GB Mesa 10.1.3
Which version of LLVM? Might be worth trying Mesa 10.2 or even current Git master if possible.