The latest checkout of the main branch of the LLVM project is 1.3GB, basically entirely text. Of that, ~900MB is tests, largely consisting of reference test vectors (this apparently isn't even the entirety of LLVM's tests, just the core ones). LLVM code itself weighs about 100MB, consisting of about 2 million lines of code (not including comments). clang (also in the same repo) is another 50MB, and about 800k lines of code. The remainder is other utilities and documentation.