New instructions mulx, adcx and adox are being introduced on Intel Architecture Processors. The adcx and adox instructions are being introduced one generation later than mulx. These new instructions will enable users to develop high-performance implementations of large integer arithmetic on Intel Architecture. To maximize performance of code using these instructions, users can program at the assembly level. However, intrinsic definitions of mulx, adcx and adox will also be integrated into compilers. This is the first example of an "Add with carry" type instruction being implemented with intrinsics. The intrinsic support will enable users to implement large integer arithmetic using higher level programming languages such as C/C++.