diff --git a/share/mk/bsd.sys.mk b/share/mk/bsd.sys.mk
index a8770cc769d2..22834aa9128e 100644
--- a/share/mk/bsd.sys.mk
+++ b/share/mk/bsd.sys.mk
@@ -6,112 +6,113 @@
 # Enable various levels of compiler warning checks.  These may be
 # overridden (e.g. if using a non-gcc compiler) by defining NO_WARNS.
 
-# for GCC:  http://gcc.gnu.org/onlinedocs/gcc-3.0.4/gcc_3.html#IDX143
+# for GCC:   http://gcc.gnu.org/onlinedocs/gcc-4.2.1/gcc/Warning-Options.html
 
 # the default is gnu99 for now
-CSTD		?= gnu99
+CSTD?=		gnu99
 
 .if ${CSTD} == "k&r"
-CFLAGS		+= -traditional
+CFLAGS+=	-traditional
 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
-CFLAGS		+= -std=iso9899:1990
+CFLAGS+=	-std=iso9899:1990
 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
-CFLAGS		+= -std=iso9899:199409
+CFLAGS+=	-std=iso9899:199409
 .elif ${CSTD} == "c99"
-CFLAGS		+= -std=iso9899:1999
-.else
-CFLAGS		+= -std=${CSTD}
-.endif
+CFLAGS+=	-std=iso9899:1999
+.else # CSTD
+CFLAGS+=	-std=${CSTD}
+.endif # CSTD
 .if !defined(NO_WARNS)
 # -pedantic is problematic because it also imposes namespace restrictions
-#CFLAGS		+= -pedantic
-. if defined(WARNS)
-.  if ${WARNS} >= 1
-CWARNFLAGS	+=	-Wsystem-headers
-.   if !defined(NO_WERROR) && ((${MK_CLANG_IS_CC} == "no" && ${CC:T:Mclang} != "clang") || !defined(NO_WERROR.clang))
-CWARNFLAGS	+=	-Werror
-.   endif
-.  endif
-.  if ${WARNS} >= 2
-CWARNFLAGS	+=	-Wall -Wno-format-y2k
-.  endif
-.  if ${WARNS} >= 3
-CWARNFLAGS	+=	-W -Wno-unused-parameter -Wstrict-prototypes\
-			-Wmissing-prototypes -Wpointer-arith
-.  endif
-.  if ${WARNS} >= 4
-CWARNFLAGS	+=	-Wreturn-type -Wcast-qual -Wwrite-strings -Wswitch\
-			-Wshadow -Wunused-parameter
-.   if !defined(NO_WCAST_ALIGN) && ((${MK_CLANG_IS_CC} == "no" && ${CC:T:Mclang} != "clang") || !defined(NO_WCAST_ALIGN.clang))
-CWARNFLAGS	+=	-Wcast-align
-.   endif
-.  endif
+#CFLAGS+=	-pedantic
+.if defined(WARNS)
+.if ${WARNS} >= 1
+CWARNFLAGS+=	-Wsystem-headers
+.if !defined(NO_WERROR) && ((${MK_CLANG_IS_CC} == "no" && \
+    ${CC:T:Mclang} != "clang") || !defined(NO_WERROR.clang))
+CWARNFLAGS+=	-Werror
+.endif # !NO_WERROR && (!CLANG || !NO_WERROR.clang)
+.endif # WARNS >= 1
+.if ${WARNS} >= 2
+CWARNFLAGS+=	-Wall -Wno-format-y2k
+.endif # WARNS >= 2
+.if ${WARNS} >= 3
+CWARNFLAGS+=	-W -Wno-unused-parameter -Wstrict-prototypes\
+		-Wmissing-prototypes -Wpointer-arith
+.endif # WARNS >= 3
+.if ${WARNS} >= 4
+CWARNFLAGS+=	-Wreturn-type -Wcast-qual -Wwrite-strings -Wswitch -Wshadow\
+		-Wunused-parameter
+.if !defined(NO_WCAST_ALIGN) && ((${MK_CLANG_IS_CC} == "no" && \
+    ${CC:T:Mclang} != "clang") || !defined(NO_WCAST_ALIGN.clang))
+CWARNFLAGS+=	-Wcast-align
+.endif # !NO_WCAST_ALIGN && (!CLANG || !NO_WCAST_ALIGN.clang)
+.endif # WARNS >= 4
 # BDECFLAGS
-.  if ${WARNS} >= 6
-CWARNFLAGS	+=	-Wchar-subscripts -Winline -Wnested-externs\
-			-Wredundant-decls -Wold-style-definition
-.  endif
-.  if ${WARNS} >= 2 && ${WARNS} <= 4
+.if ${WARNS} >= 6
+CWARNFLAGS+=	-Wchar-subscripts -Winline -Wnested-externs -Wredundant-decls\
+		-Wold-style-definition
+.endif # WARNS >= 6
+.if ${WARNS} >= 2 && ${WARNS} <= 4
 # XXX Delete -Wuninitialized by default for now -- the compiler doesn't
 # XXX always get it right.
-CWARNFLAGS	+=	-Wno-uninitialized
-.  endif
-CWARNFLAGS	+=	-Wno-pointer-sign
+CWARNFLAGS+=	-Wno-uninitialized
+.endif # WARNS >=2 && WARNS <= 4
+CWARNFLAGS+=	-Wno-pointer-sign
 # Clang has more warnings enabled by default, and when using -Wall, so if WARNS
 # is set to low values, these have to be disabled explicitly.
-.  if ${MK_CLANG_IS_CC} != "no" || ${CC:T:Mclang} == "clang"
-.   if ${WARNS} <= 3
-CWARNFLAGS	+=	-Wno-tautological-compare -Wno-unused-value\
-			-Wno-parentheses-equality -Wno-unused-function\
-			-Wno-conversion
-.   endif
-.   if ${WARNS} <= 2
-CWARNFLAGS	+=	-Wno-switch-enum -Wno-empty-body
-.   endif
-.   if ${WARNS} <= 1
-CWARNFLAGS	+=	-Wno-parentheses
-.   endif
-.   if defined(NO_WARRAY_BOUNDS)
-CWARNFLAGS	+=	-Wno-array-bounds
-.   endif
-.  endif
-. endif
+.if ${MK_CLANG_IS_CC} != "no" || ${CC:T:Mclang} == "clang"
+.if ${WARNS} <= 3
+CWARNFLAGS+=	-Wno-tautological-compare -Wno-unused-value\
+		-Wno-parentheses-equality -Wno-unused-function -Wno-conversion
+.endif # WARNS <= 3
+.if ${WARNS} <= 2
+CWARNFLAGS+=	-Wno-switch-enum -Wno-empty-body
+.endif # WARNS <= 2
+.if ${WARNS} <= 1
+CWARNFLAGS+=	-Wno-parentheses
+.endif # WARNS <= 1
+.if defined(NO_WARRAY_BOUNDS)
+CWARNFLAGS+=	-Wno-array-bounds
+.endif # NO_WARRAY_BOUNDS
+.endif # CLANG
+.endif # WARNS
 
-. if defined(FORMAT_AUDIT)
-WFORMAT		=	1
-. endif
-. if defined(WFORMAT)
-.  if ${WFORMAT} > 0
-#CWARNFLAGS	+=	-Wformat-nonliteral -Wformat-security -Wno-format-extra-args
-CWARNFLAGS	+=	-Wformat=2 -Wno-format-extra-args
-.   if !defined(NO_WERROR) && ((${MK_CLANG_IS_CC} == "no" && ${CC:T:Mclang} != "clang") || !defined(NO_WERROR.clang))
-CWARNFLAGS	+=	-Werror
-.   endif
-.  endif
-. endif
-. if defined(NO_WFORMAT) || ((${MK_CLANG_IS_CC} != "no" || ${CC:T:Mclang} == "clang") && defined(NO_WFORMAT.clang))
-CWARNFLAGS	+=	-Wno-format
-. endif
-.endif
+.if defined(FORMAT_AUDIT)
+WFORMAT=	1
+.endif # FORMAT_AUDIT
+.if defined(WFORMAT)
+.if ${WFORMAT} > 0
+#CWARNFLAGS+=	-Wformat-nonliteral -Wformat-security -Wno-format-extra-args
+CWARNFLAGS+=	-Wformat=2 -Wno-format-extra-args
+.if !defined(NO_WERROR) && ((${MK_CLANG_IS_CC} == "no" && \
+    ${CC:T:Mclang} != "clang") || !defined(NO_WERROR.clang))
+CWARNFLAGS+=	-Werror
+.endif # !NO_WERROR && (!CLANG || !NO_WERROR.clang)
+.endif # WFORMAT > 0
+.endif # WFORMAT
+.if defined(NO_WFORMAT) || ((${MK_CLANG_IS_CC} != "no" || \
+    ${CC:T:Mclang} == "clang") && defined(NO_WFORMAT.clang))
+CWARNFLAGS+=	-Wno-format
+.endif # NO_WFORMAT || (CLANG && NO_WFORMAT.clang)
+.endif # !NO_WARNS
 
 .if defined(IGNORE_PRAGMA)
-CWARNFLAGS	+=	-Wno-unknown-pragmas
-.endif
+CWARNFLAGS+=	-Wno-unknown-pragmas
+.endif # IGNORE_PRAGMA
 
 .if ${MK_CLANG_IS_CC} != "no" || ${CC:T:Mclang} == "clang"
-CLANG_NO_IAS	=	-no-integrated-as
-CLANG_OPT_SMALL	=	-mllvm -stack-alignment=8 \
-			-mllvm -inline-threshold=3 \
-			-mllvm -enable-load-pre=false \
-			-mllvm -simplifycfg-dup-ret
-.endif
+CLANG_NO_IAS=	 -no-integrated-as
+CLANG_OPT_SMALL= -mllvm -stack-alignment=8 -mllvm -inline-threshold=3\
+		 -mllvm -enable-load-pre=false -mllvm -simplifycfg-dup-ret
+.endif # CLANG
 
 .if ${MK_SSP} != "no" && ${MACHINE_CPUARCH} != "ia64" && \
     ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
 # Don't use -Wstack-protector as it breaks world with -Werror.
-SSP_CFLAGS	?=	-fstack-protector
-CFLAGS		+=	${SSP_CFLAGS}
-.endif
+SSP_CFLAGS?=	-fstack-protector
+CFLAGS+=	${SSP_CFLAGS}
+.endif # SSP && !IA64 && !ARM && !MIPS
 
 # Allow user-specified additional warning flags
-CFLAGS		+=	${CWARNFLAGS}
+CFLAGS+=	${CWARNFLAGS}