CMake Error at src/CMakeLists.txt:5 (find_package):
  Could not find a package configuration file provided by "LLVM" with any of
  the following names:

    LLVMConfig.cmake
    llvm-config.cmake

  Add the installation prefix of "LLVM" to CMAKE_PREFIX_PATH or set
  "LLVM_DIR" to a directory containing one of the above files.  If "LLVM"
  provides a separate development package or SDK, be sure it has been
  installed.

cmake_minimum_required(VERSION 2.8)
project(sample)
# 明示的にLLVM_DIRを指定するとエラーが消えるが環境依存になってしまう
set(LLVM_DIR /usr/local/Cellar/llvm/3.5.1/share/llvm/cmake)
find_package(LLVM REQUIRED CONFIG)

cmake -D LLVM_DIR=/path/to/LLVMConfig.cmake

CC=clang cmake .