Followign this website:http://llvm.org/docs/GettingStarted.html and install LLVM, the source codes lay in the examples files. I just download the header files recommanded for the tutorial cpp files.But I find that those header files' paths in the cpp files annoyed me because the path is incorrect.So I consider to copy the needed header files into the same directory. If you have better method to solve this problem, please tell me.