Actually, bcp already has a list of things it can't figure out automatically:

https://github.com/boostorg/bcp/blob/develop/add_path.cpp#L195

which would need to be updated...

... with something like https://github.com/boostorg/bcp/commit/365e5e74f1708425ae542698730076e52acb0... Unfortunately, after these fixes, everything seems to be copied correctly, but b2.exe then crashes. Something to do with `test` using `predef`, I assume, because if I delete libs/test, it then works.