The properties of high-redshift quasar host galaxies are studied in order to investigate the connection between galaxy evolution, nuclear activity, and the formation of supermassive black holes. We combine new near-IR observations of three high-redshift quasars (21.5. Radio-quiet quasar hosts also follow a similar trend but at a lower average luminosity (~0.5 mag dimmer). The data indicate that quasar host galaxies are already fully formed at epochs as early as ~2 Gyr after the big bang and then passively fade in luminosity to the present epoch.