The article mentions debug build time as a legitimate pain point about the LLVM project. General good advice, which unfortunately isn't enabled by default: use dynamic linking, make sure you're using lld, enable split dwarfs (and -Wl,--gdb-index for faster gdb load times!), enable optimized tablegen[0]. ccache doesn't hurt but isn't actually such a big benefit unless you switch between branches a lot.

Oh, and buy a Threadripper. Seriously, you won't regret it.

[0] TableGen is LLVM's internal DSL swiss army knife. You can separately enable optimizations for TableGen independently of optimizations in the resulting LLVM builds, which you should basically always do unless you're working on TableGen itself.

Do you know why isn't it easier to offload compilation to the cloud yet? Compilation is an embarrassingly parallel problem and shouldn't need take longer than than slowest file plus linking. Compilation is also a pure function (I know it's not quite set up like that in practice but it is in theory) so it's stateless and cacheable. I would have thought developers could share a massive cluster and have thousand-way compilation instantly. Doesn't seem to be a thing people are building or using in practice for some reason.