Is '--pch’ option incompatible with armclang, ARM compiler version 6?

Hi, I tried to use compile option pch (Precompiled Header) for compile time optimization. 

But it seems like armclang (ARM compiler version 6) doesn't support --pch options. 

Is there any way to use pch option in armclang?  If not, is there any recommended armclang options for compile time optimization?