  We combine six measurements of the inclusive top-quark pair (ttbar)
production cross section (sigma_ttbar) from data collected with the CDF and D0
detectors at the Fermilab Tevatron with proton anti-proton collisions at
sqrt{s} = 1.96 TeV. The data correspond to integrated luminosities of up to 8.8
fb^{-1}. We obtain a value of sigma_ttbar = 7.60 \pm 0.41 pb for a top-quark
mass of m_t=172.5 GeV. The contributions to the uncertainty are 0.20 pb from
statistical sources, 0.29 pb from systematic sources, and 0.21 pb from the
uncertainty on the integrated luminosity. The result is in good agreement with
the standard model expectation of 7.35^{+0.28}_{-0.33} pb at NNLO+NNLL in
pertubative QCD.
