GCC has support for built-in functions in C99/C11 standards along with features of IEEE standards. These functions do appropriate calculations according to the requirements of the users taking various types of arguments and returning values as required on supported data types of GCC like int, float. Such inbuilt functions help users, developers and GCC developers to minimize the repetitive calculations and efforts. There are optimization steps carried out to have faster compilation and running time of programs, folding and inlining being one of them. The purpose of this project is to implement more such functions in GCC which are added in ISO/IEC TS 18661 (supporting features of IEEE 754), folding them and expanding them inline wherever appropriate.