lldを入れるのはあくまでクロスコンパイル用で、Appleプラットフォームではld64を引き続き使い続けるはず

8:17 AM

という気持ちの現われがこちらに https://github.com/apple/llvm-project/pull/8119

[lld] Disable ability to link Mach-O for Darwin platforms (but not ...

For Embedded Swift, we want to start including lld even in Darwin toolchains to be able to link ELF files even on Darwin, see apple/swift#70715. To avoid accidentally using lld to link Mach-O files...