title: Where is the system llvm-config on macOS?
body: <p>If I'm not mistaken, the compiler etc. installed as part of XCode use llvm. But I can't find an llvm-config binary to generate proper flags for command-line compilation to an llvm target.  Where is such a thing on macOS?</p>
  
  <p>I know I can install a new llvm via MacPorts or Homebrew, but I don't want to duplicate what's already there; I just want a way to get at the system configuration.</p>