It prints/deletes .o files which should be rebuilt according to source modification times, including those of any local #includes (recursively). It assumes a flat directory structure (no include/+src/), and that object→source mapping is simple, i.e. that foo.o comes from foo.c, foo.cc or foo.cpp in the same directory. It's only ~200 lines of code if you feel like hacking it. It doesn't have a full featured pre-processor, it just looks for include lines. So it doesn't understand #ifdef or defines which is a problem if you have optional includes. The -m option, which skips "missing include files", may work for you. (See also -h for help).