At MSFT we used a Perforce fork (Source Depot), but the Windows codebase was still developed in separate repos ("depots"): kernel, shell, graphics, etc. We had

At MSFT we used a Perforce fork (Source Depot), but the Windows codebase was still developed in separate repos ("depots"): kernel, shell, graphics, etc. We had custom tooling to coordinate cross-repo changes, so it was still far from a monorepo.