In this paper we describe a general method to prove termination of C programs in a scalable and modular way. The program to analyse is reduced to the smallest relevant subset through a termination-specific slicing technique. Then, the program is divided into pieces of code that are analysed separately, thanks to an external engine for termination. The result is implemented in the prototype \stoptool over our previous toolsuite WTC [compsys-termination-sas10] and preliminary results shows the feasibility of the method.