I agree. While I like the idea of tup (https://gittup.org/tup/ -- the first "forward" build system I remember hearing of), writing a makefile is easy enough that thinking about the problem upside-down doesn't offer a compelling reason to switch.

Ptrace is one option for tracing dependencies, but it comes with a performance hit. A low-level alternative would be ftrace (https://lwn.net/Articles/608497/) or dtrace (https://en.wikipedia.org/wiki/DTrace).

Tup uses LD_PRELOAD to intercept calls to C file i/o functions. On OSX it looks DYLD_INSERT_LIBRARIES would be the equivalent.