This depends a lot on what you're doing with LLVM. If you are just using LLVM as a code generation backend for your language frontend, you generally do not need an LLVM fork.
For example, while Rust does have an LLVM fork, it just exists for tighter control over backports, not because there are any modifications to LLVM.
For example, while Rust does have an LLVM fork, it just exists for tighter control over backports, not because there are any modifications to LLVM.