Setting TimeMachine exclusions on build directories?

I've been going through this exercise of excluding a number of directories from my Time Machine backups because they often contain thousands of tiny files that are easily regenerated. This can really help speed Time Machine backups, especially first-time backups (which I find I have to do far too often). It would be handy if swift build (and maybe SPM) could set the tmexclusion flags when they create some of these temporary directories. Thoughts?