When building a Rust binary with lto=true, is there a way to limit the crates the linker examines?

The program I have ends up using over 110 crates in its build. However, the core performance gains (where 80+%) of the benefit is, resides in only a few 'crates'. Ya, I took the time to drill down through crates that used crates. Consequently, I'd like the linker to use lto options for only those 5-6 crates, rather that looking at all +110. Does anyone know if this is possible? And, if it is, how do I direct the linker to do it? Yes, the difference is just build-time, but its only going to get worse as I add more crates.