Results are reported from two searches for supersymmetric particles in final states with multiple jets, including several b-tagged jets, with and without large missing transverse momentum. The data sample corresponds to 2.3 fb-1 (2.7 fb-1 without missing transverse momentum) of pp collisions recorded by the CMS experiment at sqrt(s) = 13 TeV. The searches focus on processes with massive, high multiplicity final states, such as gluino pair production with the gluino decaying to top quarks and a neutralino, and gluino pair production with R-parity violating gluino decay to top, bottom and strange quarks. Both searches use the quantity MJ, the sum of the masses of the large-radius jets, to discriminate between signal and background, establish control regions for other discriminating variables, and as a central piece of the background estimation. The observed event yields are consistent with the standard model expectations, and the results are interpreted in terms of limits on simplified supersymmetric models. Gluinos with mass less than 1600 GeV are excluded for models with gluino decays to ttbar and neutralino with light neutralinos, and gluinos with mass less than 1360 GeV are excluded for the decay gluino to tbs.