LTO is not widely used in the distributions. However, more and more OS enable LTo by default for their packages. Is it enabled by default on your distribution - ask your maintainers.
Is LTO enabled in other binaries - ask their authors. Do not forget that enabling LTO could uncover some bugs: GentooLTO or this.
State across distributions:
Performance improvements from enabling LTO:
- Vector: vectordotdev/vector#15631 (comment)
- Ladybird: https://twitter.com/awesomekling/status/1702247511698587678
- Symbolicator: getsentry/symbolicator#1334
- pylyzer: mtshiba/pylyzer#80 (comment)
- Rustc: https://issues.fuchsia.dev/issues/42066512
- prettyplease: GitHub comment
- resvg: linebender/resvg#765 (comment)
Some LTO-only issues:
- ntpd-rs: pendulum-project/ntpd-rs#1522
- sequoia: https://gitlab.com/sequoia-pgp/sequoia/-/issues/1113
Links:
- https://convolv.es/guides/lto/
- Multiple great articles about LTO (mostly in GCC but sometimes LLVM is covered too) with A LOT of benchmarks from Honza Hubička: LTO history, GCC 4.8, GCC 4.9.1 and LLVM 3.5, GCC 5, GCC 6, GCC 8, more about GCC 8, GCC 9