title: How to make clang compile to llvm IR
body: <p>I want clang to compile my C/C++ code to LLVM bitcode rather than a binary executable. How can I achieve that?</p>
  <p>And if I have the LLVM bitcode, how can I further compile it to a binary executable?</p>
  <p>I want to add some of my own code to the LLVM bitcode before compiling to a binary executable.</p>