This is better achieved with the compiler level tooling, rather than in Make. It's pretty easy to replace `cc` with a short script that runs the pre-compiler and compares the result with a cache.

If the source code is kept tight, it doesn't yield much of a speed-up, though - precompiling hundreds of unnecessary headers can take a lot of time. Better to put some effort into moving unnecessary #includes out of header files. In fact, you can use your log of cache-hits to guide that work.