Wang, llvm-lit is supposed to run on the top of build directory, and it should be located in "bin" directory. Of course, you should build the tree in advance. $ Release+Asserts/bin/llvm-lit -v tools/clang/test /path/to/clang-srcdir/test/CodeGenOpenCL/address-spaces.cl (or bin/llvm-lit, if you are using cmake) ...Takumi