[LLD] Is branch island supported in LLD?

For ARM64, the relocation source and target is limited, like IMAGE_REL_ARM64_BRANCH26. Will LLD gerneate branch island to handle the case where the relocation is out of range? I saw there is enum value typeBranchIsland defined, but seems not implemented anywhere?

I assume you're referring to COFF. The support for that is in progress
at https://bugs.llvm.org/show_bug.cgi?id=40467.