How many CPU cores does UE4 support?

Some things like Light Building or some import algorithms has a very high CPU overhead. In the task manager I see that UE4 can fully utilize all 8 threads of my CPU (AMD Ryzen 5 1400). So it seems that UE4 has good multicore scaling. So the question is: What is the maximum number of CPU cores that UE4 can use simultaneously?

Lightmass scales pretty much infinitely across cores, BUT it cannot split up one object across multiple cores. So you might get stuck with one 2048 resolution lightmap holding the bake back from finishing.