  The inclusive $t\bar{t}$ production cross-section is measured in the
lepton+jets channel using 20.2 fb$^{-1}$ of proton--proton collision data at a
centre-of-mass energy of 8 TeV recorded with the ATLAS detector at the LHC.
Major systematic uncertainties due to the modelling of the jet energy scale and
$b$-tagging efficiency are constrained by separating selected events into three
disjoint regions. In order to reduce systematic uncertainties in the most
important background, the W+jets process is modelled using Z+jets events in a
data-based approach. The inclusive $t\bar{t}$ cross-section is measured with a
precision of 5.7% to be $\sigma_{t\bar{t}} = 248.3 \pm 0.7 \, (\mathrm{stat.})
\pm 13.4 \, (\mathrm{syst.}) \pm 4.7 \, (\mathrm{lumi.})~\text{pb}$, assuming a
top-quark mass of 172.5 GeV. The result is in agreement with the Standard Model
prediction.
