http://releases.llvm.org/3.9.0/tools/lld/docs/Readers.html Seems to indicate that many object file formats contain the information you need to split them up in such a fine-grained manner.

But maybe, they require you to create special versions of object files where even references internal to each library are referenced there as if they live in a different object file? Is that even possible?

Edit: corrections welcome, but https://github.com/llvm-mirror/lld/tree/master/lib/ReaderWri... seems to indicate that this only sopports Mach-o (and a yaml-based format used for debugging and testing)