Also same-looking issue in llvmPackages_rocm but not in other llvmPackages versions that we build. (I just confirmed that the PR doesn't fix it and reverting glibc upgrade doesn't fix it. It sounds possible that this PR triggered them.) Build links:

https://hydra.nixos.org/build/214886749
https://hydra.nixos.org/build/215014044

Originally posted by @vcunat in #209870 (comment)