Cranelift is an LLVM alternative (with its own IR), which compiles faster but has less advanced optimizations. Incidentally, I believe it’s written in Rust. Anyway, rust will soon use Cranelift to generate its code in debug mode. Since most of LLVM’s optimizations are off in debug mode anyway, this should mean shorter compile times while you’re building your project at little cost to runtime performance while you’re developing (and no cost at all to end users, who won’t be using debug builds).