The mechanical properties of a homologous series of polyolefin block copolymers comprised of glassy poly(cyclohexylethylene) (C), elastomeric poly(ethylene-alt-propylene) (P), and semicrystalline poly(ethylene) (E) are documented. Monodisperse CPEPC, CPE, and CEPEC with mass fractions w(C) similar to 0.39-0.44 and 0 <= xi <= 1, where xi = w(E) /(w(E) + w(P)), were synthesized by sequential anionic polymerization of styrene, isoprene, and butadiene followed by catalytic hydrogenation. These materials hierarchically microphase separate into lamellae, within which templated crystallization-induced segregation occurs. As xi increases, the unoriented, polydomain CPEPC materials exhibit monotonically increasing elastic moduli and yield stresses, comparable ultimate tensile strengths, and decreasing failure strains. Cold drawing the CPEPC polymers yields high-strength materials, the structures of which are examined by small- and wide-angle X-ray scattering. Drawn CPEPC-70 (xi = 0.70) exhibits improved toughness with an ultimate tensile strength sigma(fail) = 75 +/- 10 MPa and elongation at break of epsilon(fail) = 1.22 +/- 0.22, as compared to sigma(fail) = 92 +/- 21 MPa and epsilon(fail) = 0.86 +/-0.18 for drawn CEC (xi = 1.00). Elasticity measurements on the drawn samples demonstrate that materials with xi > 0 exhibit low degrees of stress softening, while smaller permanent sets and higher failure strains are observed as xi decreases.