[cfe-dev] Building clang outside of LLVM (with CMake)

[Óscar Fuentes]

Some time ago Doug mentioned that it would be useful to build clang
outside of LLVM: basically LLVM acts as an external library which is
used by clang.

Just to be sure that I'm working on the right track, what's the
motivation for this requirement?

IIRC Doug mentioned something about build times, and indeed clang takes
about 4 minutes to build alone and almost 10 minutes to build within
LLVM, so if the goal is to quickly build clang multiple times with the
same LLVM base then it is a must-have feature.