Performance libraries are the building blocks of high performance applications. These libraries, architecture-dependent, are mostly hand-tuned. On-going research efforts have led to the design of automatic library generators such as ATLAS for linear algebra functions, SPIRAL or FFTW for signal processing and DFT functions. These generators, domain-specific, automatically tune the code according to the target architecture features. In this talk I will present a new approach for the generation of performance libraries. This approach is not application-specific: it relies on performance measures of source code kernels and on a very simple performance model in order to build library functions from these building blocks. Performance results will be compared with ATLAS and vendor libraries on Itanium2 and Pentium architectures. Challenges of this approach, in particular of the performance model, will be discussed.