Part I
Clang Setup and Architecture
You can find some info about LLVM internal architecture and how Clang fits into it. There is also description how to install and build Clang and Clang-Tools, description for basic LLVM libraries and tools used across LLVM project and essential for Clang development. You can find description for some Clang features and their internal implementation.
This part has the following chapters:
Chapter 1, Basic Libraries and Tools
Chapter 2, Clang Architecture
Chapter 3, Clang AST
Chapter 4, Basic Libraries and Tools