Copyright question - Using part of the LLVM codebase

Hi LLVM folks,

I’m planing to use part of the ADT library code in my Apache2.0 open source project. Particularly, one of the classes in llvm/ADT/STLExtras.h.
What should I do? Do I need to include LLVM’s license file in root directory of my project? Or just add the copyright file header before the target class?

I’d read the "Developer Policy” website but seems that it only mention “redistribution”, which (in my point of view) looks like distribute a customized version of LLVM instead of using only small part of it.

Best Regards,
Bekket McClane