I have made unofficial version RC1 of CentOS6 RPMs.
https://github.com/llvm-project/llvm-project-20170507/releases/tag/release_600_rc1
It includes;
20.9 MB clang-6.0.0-1.el6.x86_64.rpm
689 KB clang-format-6.0.0-1.el6.x86_64.rpm
500 KB libc.-6.0.0-1.el6.x86_64.rpm
480 KB libc.-devel-6.0.0-1.el6.noarch.rpm
122 KB libc.abi-6.0.0-1.el6.x86_64.rpm
12.8 MB lld-6.0.0-1.el6.x86_64.rpm
Let me know if any issues were there.
They might be available on newer version of centos or fedora. I cannot check them atm.
Thanks,
Takumi