All library files (viz. libm.a, libc.a ...etc) are present in the ewl\lib folder.
The following steps help rebuild the EWL library files on the command prompt.
For example, if your Kinetis product layout is in the folder C:\Freescale\CW MCU v10.x then you can define CWINSTALL as follows:
set CWINSTALL='C:\Freescale\CW MCU v10.x'
cd C:\Freescale\CW MCU V10.x\MCU\ARM_EABI_Support\ewl
You could skip the <path_to_make_utility> if you have make in your PATH variable.
make -s -f makefile PLATFORM=ARM_CORTEXM all cleanobj
The PLATFORM=ARM_CORTEXM indicates that EWL is being re-built for Kinetis. After the make command is complete, check the lib folder and its sub-folders for the presence of libm.a, libc.a, ...etc.