cmake_minimum_required( VERSION 3.6 )

function(BUILD_SIMULINK model)

   set(OUTPUT_FILE ${model}.dll)
   set(SOURCE_FILE ${model}.slx)
   set(EXECUTE_COMMAND
      matlab -nojvm -nodisplay -nodesktop -nosplash -wait -r "rtwbuild(${model})"
   )

   add_custom_target(
      ${model}  ALL
      DEPENDS  ${OUTPUT_FILE}
   )

   add_custom_command(
      COMMAND    ${EXECUTE_COMMAND}
      DEPENDS    ${SOURCE_FILE}
      OUTPUT     ${OUTPUT_FILE}
   )

   install( TARGETS ${OUTPUT_FILE}
            DESTINATION lib
   )

endfunction(BUILD_SIMULINK)

project(SimulinkBuild VERSION 1.0.0)
build_simulink( model1 )
build_simulink( model2 )
build_simulink( model3 )
...
build_simulink( modeln )  # Arbitrarily large number of models

cmake ..
cmake --build . --target install

cmake ..
cmake --build . -- /m  # Visual Studio
cmake --build . -- -j  # Gnu make

cmake --build . --target install -j <number of threads>

cmake --build . --target install -- -j <number of threads>

cmake --build . --target install -- /m <number of threads>