To update an existing LLVM build, you can take the following steps:
Make sure that your source code directory is up to date by synchronizing it with the LLVM repository.
Enter your existing build directory.
Run CMake in the build directory again to re-configure the build.
Build LLVM again by executing the build command.
If necessary, reinstall LLVM using the install command.
This process ensures that any changes in the LLVM source code are applied to your existing build, maintaining consistency.