https://bugs.freedesktop.org/show_bug.cgi?id=87059
--- Comment #5 from smoki smoki00790@gmail.com --- (In reply to Jarkko K from comment #3)
[Properties] "opengl.version"="3.0 Mesa 10.5.0-devel (git-d8da6de 2014-12-06 trusty-oibaf-ppa)"
That ppa still use llvm-3.5, OK. Yes i manage to reporuduce it now with llvm-3.5 and with GFX Quality high setted in game, but with low issue is not there.
Anyway issue as i see is mostly fixed if current mesa is compiled against llvm-3.6 svn.
I don't use ubuntu but you might want to try some ppas which does that like this one - not day to day up to date, but hopefully should work at least for you to check if this issue still appear there for you?
https://launchpad.net/~paulo-miguel-dias/+archive/ubuntu/mesa