"We intend to keep LLVM perpetually open source and to use a liberal open source license. As a contributor to the project, you agree that any contributions be licensed under the terms of the corresponding subproject. All of the code in LLVM is available under the University of Illinois/NCSA Open Source License, which boils down to this:
You can freely distribute LLVM.
You must retain the copyright notice if you redistribute LLVM.
Binaries derived from LLVM must reproduce the copyright notice (e.g. in an included readme file).
You can’t use our names to promote your LLVM derived products.
There’s no warranty on LLVM at all.
We believe this fosters the widest adoption of LLVM because it allows commercial products to be derived from LLVM with few restrictions and without a requirement for making any derived works also open source (i.e. LLVM’s license is not a “copyleft” license like the GPL). We suggest that you read the License if further clarification is needed."