Partial "compilation"

In my current setup I have my main project A that is consuming library B. Project A is being run through r.js and it generates bundles for library B along the process. Library B is getting quite big, and I'm thinking it's worth it to bundle (parts of perhaps) it as part of its build process.

That would leave Project A consuming library B, alongside with a bundles config to know what's in B's bundle. Is it possible to do something like this currently? I would have to spend a few days trying to get this working if it's not really supported.