How to load an external pass in lld now?

I am using lld 15 and with changes approx 2 weeks ago my passes are not loaded anymore.

I use -mllvm=-load=foo.so --lto-debug-pass-manager and the pass is not being shown processed in any way. debug output for lots of other passes are printed though. Also no message that the pass could not be loaded is written.

I believe -load is a legacy PM option, you need to use -load-pass-plugin with the new pass manager.

If I pass -load-pass-plugin via clang, would that be -Wl,--load-pass-plugin=./foo.so? because this isnt loading the pass either (no mentioning the pass anywhere in the debug output, also no error/warnings about it)