title: Cmake errors when using LLVM 5.0.0 from brew
body: <p>I'm trying to use the stock LLVM 5.0.0 provided by Homebrew (MacOS High Sierra 10.13.3). LLVM is installed on my machine under <code>/usr/local/Cellar/llvm/5.0.0/</code></p>
  
  <p>Now, in my project, I have the following lines in <code>CMakeLists.txt</code>:</p>
  
  <pre><code># Find the LLVM library
  find_package( LLVM 5.0.0 REQUIRED )
  include_directories( "${LLVM_INCLUDE_DIRS}" )
  link_directories(${LLVM_LIBRARY_DIRS})
  message(STATUS "LLVM include dirs: ${LLVM_INCLUDE_DIRS}")
  </code></pre>
  
  <p>If I run CMake without any parameters, I get:</p>
  
  <blockquote>
    <p>CMake Error at CMakeLists.txt:74 (find_package):
     By not providing "FindLLVM.cmake" in CMAKE_MODULE_PATH this project has
     asked CMake to find a package configuration file provided by "LLVM", but
     CMake did not find one.</p>
    
    <p>Could not find a package configuration file provided by "LLVM" (requested
     version 5.0.0) with any of the following names:</p>
  
  <pre><code>LLVMConfig.cmake
  llvm-config.cmake
  </code></pre>
    
    <p>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.</p>
  </blockquote>
  
  <p>It tells me that it couldn't find LLVM. So, I pass the path to the LLVM_DIR, like this:</p>
  
  <pre><code>cmake .. -DLLVM_DIR=/usr/local/Cellar/llvm/5.0.0/share/cmake/modules/
  </code></pre>
  
  <p>I would expect everything to work. Instead I get the following error:</p>
  
  <blockquote>
    <p>CMake Error at CMakeLists.txt:74 (find_package):
     Could not find a configuration file for package "LLVM" that is compatible
     with requested version "5.0.0".</p>
    
    <p>The following configuration files were considered but not accepted:</p>
    
    <p>/usr/local/Cellar/llvm/5.0.0/share/cmake/modules/llvm-config.cmake,
       version: unknown</p>
  </blockquote>
  
  <p>For some reason the version is not present anywhere in the <code>share/cmake/modules</code> directory.</p>
  
  <p>How can I fix this, without changing the brew-installed LLVM?</p>