a project of Eta Labs
libc-bench is a set of time- and memory-efficiency tests to compare implementations of various C/POSIX standard library functions. Coverage includes:
Latest releases are available here.
You can also browse the current source.
At present I have not collected any scientific results. Some results from key tests on my particular test machine are included in the libc comparison page. Compiling a set of results for a much broader collection of libc implementations (for example, BSDs and proprietary systems) as well as different CPU architectures and variants would be quite an interesting project, and unfortunately one for which I do not have the time or resources.