When using LTO, lld must have the exact same version as LLVM, because LLVM IR isn't compatible across versions. An older version of lld won't be able to link IR files generated by a newer LLVM, and vice versa. Since LLVM and Clang are slotted, this essentially means only one of the installed Clang versions will function properly with lld. Reproducible: Always
*** This bug has been marked as a duplicate of bug 691900 ***