These instructions will allow you to easily checkout the latest source of LLVM, including the clang compiler and various tools.
To checkout the LLVM source tree, get the repo tool: https://source.android.com/source/downloading.html#installing-repo
For the initial checkout of the source tree, perform the following steps:
# mkdir llvm
# cd llvm
# repo init -u https://github.com/markun/llvm-repo.git
# repo sync
To update the source tree, enter the llvm directory and do:
# repo sync
To build LLVM, follow the instructions at: http://llvm.org/docs/CMake.html