c# – clang compiler is not working for ‘opt’ command

opt command not working for CLANG compiler, installed CLANG and LLVM, after I ran ‘clang++ -emit-llvm -S test.cpp -o prog.ll’ it is working well and good but once I tried running the the ‘opt’ opt –dot-cfg prog.ll I am getting the error as ”opt’ is not recognized as an internal or external command,
operable program or batch file.’