Why not use LLD for linking Rust? You already must have the LLVM for Rust to be buildable, so that do not add any dependency.

Agreed -- not my wheelhouse, but couldn't you just build rust earlier in your process using LLD, then build mold, then build everything else?

Would that meant that building rust is slower, but everything else is the same, and you don't have to maintain a fork of another complex project?

Because mold is faster. Linking is a significant bottleneck when building large projects.