Surprising that this topic has (as of now) 60 point and only two comments.

At Taodyne, we use LLVM as the foundation for our 3D dynamic document description language. This makes it possible to do interesting things in real-time, see e.g. http://www.taodyne.com/shop/en/blog/58-live-coding-creating-.... LLVM is pretty powerful, and now relatively stable as far as even the C++ API is concerned. In earlier days, having the C++ API change underneath you in significant way at every release was a real pain.

That being said, I was not a real fan of their documentation in general, and the Kaleidoscope tutorial was no exception. But it looks like they are putting a lot of effort into this, and it looks much much better than it used to.