Thank you very so much for this!

I had to fight a bit with my llvm an clang setup on Ubuntu 14.10. Make sure to install everything in version 3.5 llvm-3.5 clang-3.5, and so on. Then run update-alternatives so cmake and make does not complain about missing binaries, you will need llvm-config, clang, llvm and perhaps other. Also, it is so important that you install ocl-icd-dev, 

ocl-icd-libopencl1 and ocl-icd-opencl-dev otherwise nothing will link.

If you installed AMD or Intel SDK/runtimes, make sure to delete them prior to anything, and force reinstall of ocl-* since the Intel and AMD stuff break your env.