I have recently compiled the -rc1 on MacOS 10.12, and the process has basically remained unchanged from 1.4. Here's a gist with my notes: https://gist.github.com/MatthiasWinkelmann/41dd42b07f8bd794a...

(I still used CUDA 8, but 9 should also work. You just need to find the version of the command line tools it works with)