llbuild is a set of libraries for building build systems. Unlike most build
system projects which focus on the syntax for describing the build, llbuild
is designed around a reusable, flexible, and scalable general purpose build
engine capable of solving many "build system"-like problems. The project
also includes additional libraries on top of that engine which provide
support for constructing bespoke build systems (like swift build) or for
building from Ninja manifests.

WWW: https://github.com/apple/swift-llbuild