Install the LLVM libraries. I've used llvm-7 so far, see http://apt.llvm.org/ for LLVM repositories.
sudo apt-get install llvm-7-dev llvm-7-tools
Then run these commands to configure
./autogen.sh && ./configure --enable-sdl --enable-qt --enable-llvm --prefix=$PWD/local
And a clean build of course.
make clean && make -j4 install