Building Clang from source

If you would like to build Clang (and lld) from source for testing purposes, it is really easy! You should have cmake and ninja installed from your distribution.

$ git clone git://github.com/llvm/llvm-project
$ cd llvm-project
$ mkdir build
$ cd build
$ cmake -G Ninja \
        -DCMAKE_BUILD_TYPE=Release \
        -DLLVM_ENABLE_PROJECTS="clang;lld;compiler-rt" \
        -DLLVM_ENABLE_WARNINGS=OFF \
        ../llvm
$ ninja

You are interested in more optimized binaries and faster compile times? You are invited to use tc-build!

$ git clone https://github.com/ClangBuiltLinux/tc-build
$ cd tc-build
$ ./build-llvm.py

If you do not have as powerful of a machine or are time restricted in some other way, you can build just Clang and LLD in a "stage 1" configuration (rather than the default of building a smaller clang and lld to build a fuller LLVM toolchain afterwards).

$ ./build-llvm.py --projects clang lld --build-stage1-only

Please see that repo's README for more information on properly using it.