State of LTO support for Swift?

Following on from the topic Pitch: Support LTO for Swift, I would like to ask if any progress has been made for Link Time Optimization for Swift, with the goal of reducing the binary size of Swift programs on Linux and Windows when using static linking (which is, to my knowledge, not yet available on Windows). (There has also been some mentioning about LTO in discussions about embedded Swift and in the topic Antimony: exploring alternative build systems .) Thanks!