  Results of a search for nonresonant production of Higgs boson pairs, with
each Higgs boson decaying to a $\mathrm{b\overline{b}}$ pair are presented.
This search uses data from proton-proton collisions at a centre-of-mass energy
of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$,
collected by the CMS detector at the LHC. No signal is observed, and a 95%
confidence level upper limit of 847 fb is set on the cross section for standard
model nonresonant Higgs boson pair production times the squared branching
fraction of the Higgs boson decay to a $\mathrm{b\overline{b}}$ pair. The same
signature is studied, and upper limits are set, in the context of models of
physics beyond the standard model that predict modified couplings of the Higgs
boson.
