By testing llvm I could not compile llvm 3.8 because of the wrong version of cmake
Centos 7 2.8.11-5.el7
Centos 6.7 - 2.8.12.2-4.el7.centos (recompile same revision)
build done im my repo to get wheel....
http://centos.cms4all.org/centos/7/llvm/SRPM/
Sincerely
Andy