title: No -debug flag for llvm opt
body: <p>I am using "Support/Debug.h" to introduce debug statements in my pass. In order to enable the debug mode, I am required to run opt with the -debug flag, however opt has no such flag. </p>
  
  <pre><code>opt: Unknown command line argument '-debug'.  Try: 'opt -help'
  opt: Did you mean '-debugify'?
  </code></pre>
  
  <p>I tried both with the releasebuild and the debugBuild version of the opt binary. </p>