  The results of a search for supersymmetry in final states containing at least
one isolated lepton (electron or muon), jets and large missing transverse
momentum with the ATLAS detector at the Large Hadron Collider (LHC) are
reported. The search is based on proton-proton collision data at a
centre-of-mass energy $\sqrt{s} = 8$ TeV collected in 2012, corresponding to an
integrated luminosity of 20 fb$^{-1}$. No significant excess above the Standard
Model expectation is observed. Limits are set on the parameters of a minimal
universal extra dimensions model, excluding a compactification radius of
$1/R_c=950$ GeV for a cut-off scale times radius ($\Lambda R_c$) of
approximately 30, as well as on sparticle masses for various supersymmetric
models. Depending on the model, the search excludes gluino masses up to 1.32
TeV and squark masses up to 840 GeV.
