In the second phase of the LHC physics program, the accelerator will provide to CMS an additional integrated luminosity of about 2500 fb − 1 over 10 years of operation, starting in 2025. It is important to keep the efficiency of the L1 muon triggers high, while maintaining pt thresholds low enough to collect a large fraction of Higgs, top quark, and electroweak bosons for more sophisticated analysis. Additional muon detectors will be installed in the forward region 1.6 < | η | < 2.4 to increase redundancy and enhance the trigger and reconstruction capabilities. In the 3rd and 4th muon stations, improved RPC (iRPC) detectors, denoted RE3/1 and RE4/1, will provide much-needed redundancy, with benefits to neutron-induced back-ground reduction for the trigger and offline reconstruction. An overwiev for the CMS Phase-II Upgrade of the Muon System is presented, particulary for the iRPCs.