How to pass compiler options during Linux kernel compilation?

From Linux kernel's makefile:

# Add any arch overrides and user supplied CPPFLAGS, AFLAGS and CFLAGS as the
# last assignments
KBUILD_CPPFLAGS += $(ARCH_CPPFLAGS) $(KCPPFLAGS)
KBUILD_AFLAGS   += $(ARCH_AFLAGS)   $(KAFLAGS)
KBUILD_CFLAGS   += $(ARCH_CFLAGS)   $(KCFLAGS)

So, passing additional options for Kbuild uses usual environment/makefile variables but with K prefix:

make "KCFLAGS=-pipe -Wsomething"