OpenLIBM is an effort to have a high quality standalone LIBM library. It is meant to be used standalone in applications and programming language implementations.
OpenLibm builds on Linux, Mac OS X, and Windows, and with little effort, should build on FreeBSD as well. It builds with both, GCC and clang.
The OpenLIBM code derives from the FreeBSD msun implementation, which in turn derives from FDLIBM 5.3. As a result, it has a number of fixes and updates that have accumulated over the years in msun, and also optimized assembly versions of many functions.