Instead, here's how to install LLVM/clang
Run the following scripts inside the directory where you want to install llvm, clang, and ninja. After running the scripts, you will have two directories -- llvm and build.
If you want to add a tool to clang, navigate to /llvm/tools/clang/tools/extra/ and create a folder that has the name of your tool. Copy one of the CMakeLists.txt from a different tool in the extra folder and modify it to include your <tool_name>.cpp file in your newly-created extra/<tool_name> directory.
To compile the tool, go to the /build directory and run "sudo ninja".
To run the tool, change directory into /build and run the command
bin/<tool_name> input_file.c --
Where the presence/name of the input file is dependent on your tool.