After a successful data taking period at the CERN LHC by the major physics experiments (ALICE, ATLAS, CMS and LHCb) since 2009, a long-term plan is already envisaged to fully exploit the vast physics potential of the Large Hadron Collider (LHC) within the next two decades. The CERN accelerator complex will undergo a series of upgrades leading ultimately to increase both the collision energy and the luminosity, thus maximizing the amount of data delivered to all experiments. As a consequence, the experiments have also to cope with very high detector occupancies and operate in the hard radiation environment caused by a huge multiplicity of particles produced in each beam crossing. In parallel to the accelerator upgrades, the LHC experiments are planning various upgrades to their detector, trigger, and data acquisition systems. The main motivation for the upgrades is to extend and to improve their physics programme also in the increasingly challenging LHC environment. In this paper a general overview of the upgrade programme of the major experiments at LHC will be given, with some additional details concerning specifications and physics programme of new detector subsystems.