llvm-2.9-doc binary package in Ubuntu Precise amd64

 The Low-Level Virtual Machine (LLVM) is a collection of libraries and
 tools that make it easy to build compilers, optimizers, Just-In-Time
 code generators, and many other compiler-related programs. LLVM
 uses a single, language-independent virtual instruction set both
 as an offline code representation (to communicate code between
 compiler phases and to run-time systems) and as the compiler internal
 representation (to analyze and transform programs). This persistent
 code representation allows a common set of sophisticated compiler
 techniques to be applied at compile-time, link-time, install-time,
 run-time, or "idle-time" (between program runs).
 .
 This package contains all documentation (extensive).

Source package