It does not use any LLVM libraries and has no feature specific to LLVM, so I think it simply doesn't have a reason to be a subproject of it (or some other large umbrella project).
Rui, regarding -- "a sponsor who wants to purchase the copyright of this work and relicense it under a more liberal license such as the MIT license." Would you accept sponsorship for someone who wants to relicense under LLVM(apache)? And do you have a ballpark asking price?