In this talk we will share our experience in the journey of transitioning Cisco Enterprise Networking software with a high market share to Clang/LLVM as the primary compiler. For performance and business reasons, our software stack should run on many different processors. We will describe several contributions to the MIPS and PPC backends to make LLVM on parity with gcc compiler for these processors. We will summarize our contributions to debugging optimized code and enabling LLVM on Cisco data plane component where code must be highly optimized with LTO to forward network packets in the correct byte order.