Low Level Virtual Machine (http://llvm.cs.uiuc.edu) (LLVM) is a compiler infrastructure designed for compile-time, link-time, run-time, and "idle-time" optimization of programs from arbitrary programming languages. It currently supports the compilation of C and C++ programs, using front-ends derived from version 3.4 of the GNU Compiler Collection (GCC).

LLVM includes aggressive interprocedural optimization support, static and JIT compilers, and has many components in various stages of development (including Java bytecode and MSIL frontends, a Python frontend, a new graph coloring register allocator, and more). LLVM is a very modular and well documented (http://llvm.org/docs) compiler, and is highly suitable for experimentation and extension.

LLVM is written in C++ and has been developed since 2000 at the University of Illinois. It is publicly available under the University of Illinois Open Source License (http://www.opensource.org/licenses/UoI-NCSA.php), an OSI-approved license that is very similar to the BSD license.

December 2004: LLVM 1.4 (http://llvm.org/) is available