So far this has worked for me, so I was able to setup ninja to build clang. $ cd llvm/llvm-build $ cmake -G Ninja ../ -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ Now it's building fine. Thanks all for the inputs. $ ninja [1/1809] ... $ ninja clang [1/1396] Which seems less and better. :-) -- Thiago