LLVM code base is huge, for beginners it would be good to generate tags files to aid reading source code. In some projects, there is a Makefile rule that generates tags file. I am wondering if LLVM has that.
A lot of people use https://clangd.llvm.org/. The actual configuration will depend on the editor that you use. In general, it relies on a compilation database which you can generate by setting CMake’s CMAKE_EXPORT_COMPILE_COMMANDS. It more or less works out of the box 
.
Happy to help if you hit a specific problem.
HTH,
-Andrzej