Any advise on update the llvm libary to new version

I’m try to update llvm libary to newer version on a LLVMGPU project. when the project was created, the engineers use the llvm-3.7 as the codebase. Now , llvm is reach to 13.0 , and there are lots of Passes was introduced and lots of bugs was fixed In the past few years. So I want to update the llvm to newer version to skip some potential bugs and to make our code keep up with commutity. Unfortunately, I don’t have much experience in updating large software systems such as llvm. I believe this question will be of great value to others as well. Do you have any suggestions or advises? Any comments are welcome.