lld contains two linkers whose architectures are different from each other.
lld is available in the LLVM SVN repository:
svn co http://llvm.org/svn/llvm-project/lld/trunk lld
lld is also available via the read-only git mirror:
git clone http://llvm.org/git/lld.git
Put it in llvm’s tools/ directory, rerun cmake, then build target lld.