Measurements are presented of the lifetimes of the ${\mathrm {B}^0}$ , $\mathrm {B}^0_\mathrm {s}$ , $\mathrm {\Lambda }\mathrm {b} ^0$ , and $\mathrm {B}\mathrm {c}^+$ hadrons using the decay channels ${\mathrm {B}^0}!\rightarrow ! \mathrm {J}/\psi \mathrm {K^{}(892)}{}^{0}$ , ${\mathrm {B}^0}!\rightarrow ! \mathrm {J}/\psi \mathrm {K^0_S}$ , $\mathrm {B}^0_\mathrm {s} !\rightarrow ! \mathrm {J}/\psi \mathrm {\pi ^+}\mathrm {\pi ^-}$ , $\mathrm {B}^0_\mathrm {s} !\rightarrow ! \mathrm {J}/\psi \mathrm {\phi (1020)}$ , $\varLambda \mathrm {b}^0!\rightarrow !\mathrm {J}/\psi \mathrm {\Lambda }^{0}$ , and $\mathrm {B}\mathrm {c}^+ !\rightarrow !\mathrm {J}/\psi \mathrm {\pi ^+}$ . The data sample, corresponding to an integrated luminosity of 19.7 $,\text {fb}^\text {-1}$ , was collected by the CMS detector at the LHC in proton–proton collisions at $\sqrt{s}=8,\text {Te}\text {V} $ . The ${\mathrm {B}^0}$ lifetime is measured to be $453.0 \pm 1.6,\text {(stat)} \pm 1.8,\text {(syst)} ,\upmu \text {m} $ in $\mathrm {J}/\psi \mathrm {K^{}(892)}{}^{0}$ and $457.8 \pm 2.7,\text {(stat)} \pm 2.8,\text {(syst)} ,\upmu \text {m} $ in $ \mathrm {J}/\psi \mathrm {K^0_S}$ , which results in a combined measurement of $c\tau {{\mathrm {B}^0}} = 454.1 \pm 1.4,\text {(stat)} \pm 1.7,\text {(syst)} ,\upmu \text {m} $ . The effective lifetime of the $\mathrm {B}^0\mathrm {s}$ meson is measured in two decay modes, with contributions from different amounts of the heavy and light eigenstates. This results in two different measured lifetimes: $c\tau {\mathrm {B}^0\mathrm {s} \rightarrow \mathrm {J}/\psi \mathrm {\pi ^+}\mathrm {\pi ^-}} = 502.7 \pm 10.2,\text {(stat)} \pm 3.4,\text {(syst)} ,\upmu \text {m} $ and $c\tau {\mathrm {B}^0\mathrm {s} \rightarrow \mathrm {J}/\psi \mathrm {\phi (1020)}} = 443.9 \pm 2.0,\text {(stat)} \pm 1.5,\text {(syst)} ,\upmu \text {m} $ . The $\mathrm {\Lambda }\mathrm {b} ^0$ lifetime is found to be $442.9 \pm 8.2,\text {(stat)} \pm 2.8,\text {(syst)} ,\upmu \text {m} $ . The precision from each of these channels is as good as or better than previous measurements. The $\mathrm {B}\mathrm {c}^+$ lifetime, measured with respect to the ${\mathrm {B}^{+}}$ to reduce the systematic uncertainty, is $162.3 \pm 7.8,\text {(stat)} \pm 4.2,\text {(syst)} \pm 0.1,(\tau _{{\mathrm {B}^{+}}}),\upmu \text {m} $ . All results are in agreement with current world-average values.