Fastbuild https://www.fastbuild.org/docs/home.html is the free distributed compilation system many game companies use. The combination of automatic unity builds (simply appending many .cpp source files together into very large combined files), caching and distributed compilation together gives you extremely fast C++ builds.
Also supports creating project files that are compatible with XCode and Visual Studio so you can just build from those IDE's and a pretty flexible dependency based build file format that can accomodate any kind of dependency.
Someone just linked Fastbuild few days ago in one community i follow and i did take a look as i havent heard about that project before. I didnt really like the idea that it would need to have its own build rules but its understandable - where as distcc would just integrate directly to what ever build tool you would be using. Also the syntax didnt look so "pleasing" but i guess the behefits can out weight the learning curve of yet an another build language (compared to meson/bazel/cmake et al) ..
Having distributed builds on msvc thought with free software sounded very promising thought.
Also supports creating project files that are compatible with XCode and Visual Studio so you can just build from those IDE's and a pretty flexible dependency based build file format that can accomodate any kind of dependency.