Install LLVM

Grab the llvm source from here. Make sure you grab the source!

Extract the source using

tar -xvf llvm-3.6.1.src.tar.xz

Make a directory outside of the source directory

mkdir llvm-build
cd llvm-build

Run the configure script (from the llvm source directory) and specify the install location

./../configure --prefix=/usr/local/

If you want to use a different location, be sure to change the compileandlink.sh script after building the Xcode project as described in the Readme.

Next build and install the source

make
make install

All done!