A search for narrow resonances at high mass in the dimuon and dielectron channels has been performed by the CMS experiment at the CERN LHC, using pp collision data recorded at $ \sqrt {s} = 7 $ TeV. The event samples correspond to integrated luminosities of 40 pb−1 in the dimuon channel and 35 pb−1 in the dielectron channel. Heavy dilepton resonances are predicted in theoretical models with extra gauge bosons (Z′) or as Kaluza-Klein graviton excitations (GKK) in the Randall-Sundrum model. Upper limits on the inclusive cross section of Z′(GKK) → ℓ + ℓ − relative to Z → ℓ + ℓ − are presented. These limits exclude at 95% confidence level a Z′ with standard-model-like couplings below 1140GeV, the superstring-inspired Z ψ ′ below 887 GeV, and, for values of the coupling parameter $ {{k} \left/ {{{{\overline M }_{\text{Pl}}}}} \right.} $ of 0.05 (0.1), Kaluza-Klein gravitons below 855 (1079) GeV.