In case anyone has the same problem (most likely not using nix), The problem is no fixed in clang >=10 and the patch will be applied in nixpkgs (clang_7,clang_8,clang_9: fix compilation of HIP-code by DieGoldeneEnte · Pull Request #78308 · NixOS/nixpkgs · GitHub). Another simple fix is to just create a derivation and symlink the missing binaries (needed: llvm-link, lld, llc, opt, maybe also clang-offload-bundler for clang >7).