llvm dev - Mar 2013 - [LLVMdev] How to set linker in cmake of llvm project?

I build the newest llvm from svn on iMac by set compiler and compiler flag as
follows,

cmake -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_C_COMPILER=clang
-DCMAKE_CXX_FLAGS=-std=c++11\ -stdlib=libc++ -DCMAKE_BUILD_TYPE=Debug -G
"Xcode"

But how to set LINK to clang++? The default is ld in Xcode of llvm project.

Jonathan