diff --git a/cddl/lib/libzpool/Makefile b/cddl/lib/libzpool/Makefile
index 9361d352f7c..0c680367956 100644
--- a/cddl/lib/libzpool/Makefile
+++ b/cddl/lib/libzpool/Makefile
@@ -281,7 +281,6 @@ CFLAGS+=	-DWANTS_MUTEX_OWNED
 CFLAGS+=	-I${SRCTOP}/lib/libpthread/thread
 CFLAGS+=	-I${SRCTOP}/lib/libpthread/sys
 CFLAGS+=	-I${SRCTOP}/lib/libthr/arch/${MACHINE_CPUARCH}/include
-CFLAGS.gcc+=	-fms-extensions
 
 LIBADD=		md pthread z spl icp nvpair avl umem
 
diff --git a/cddl/usr.bin/ztest/Makefile b/cddl/usr.bin/ztest/Makefile
index 83c7b0eee13..89ee381f38e 100644
--- a/cddl/usr.bin/ztest/Makefile
+++ b/cddl/usr.bin/ztest/Makefile
@@ -28,7 +28,6 @@ CSTD=	c99
 # Since there are many asserts in this program, it makes no sense to compile
 # it without debugging.
 CFLAGS+= -g -DDEBUG=1 -Wno-format -DZFS_DEBUG=1
-CFLAGS.gcc+= -fms-extensions
 
 HAS_TESTS=
 SUBDIR.${MK_TESTS}+= tests
diff --git a/cddl/usr.sbin/zdb/Makefile b/cddl/usr.sbin/zdb/Makefile
index 8bf07cb4c06..239299aa1d6 100644
--- a/cddl/usr.sbin/zdb/Makefile
+++ b/cddl/usr.sbin/zdb/Makefile
@@ -24,7 +24,6 @@ CFLAGS+= \
 
 LIBADD=	nvpair umem zdb zfs_core zfs spl avl zutil zpool crypto pthread
 
-CFLAGS.gcc+= -fms-extensions
 # Since there are many asserts in this program, it makes no sense to compile
 # it without debugging.
 CFLAGS+=	-g -DDEBUG=1 -DZFS_DEBUG=1
diff --git a/sys/conf/kern.pre.mk b/sys/conf/kern.pre.mk
index 3dc1efe3d5d..a5b21cdbe84 100644
--- a/sys/conf/kern.pre.mk
+++ b/sys/conf/kern.pre.mk
@@ -78,10 +78,9 @@ CFLAGS=	${COPTFLAGS} ${DEBUG}
 CFLAGS+= ${INCLUDES} -D_KERNEL -DHAVE_KERNEL_OPTION_HEADERS -include opt_global.h
 CFLAGS_PARAM_INLINE_UNIT_GROWTH?=100
 CFLAGS_PARAM_LARGE_FUNCTION_GROWTH?=1000
-CFLAGS.gcc+= -fms-extensions -finline-limit=${INLINE_LIMIT}
+CFLAGS.gcc+= -finline-limit=${INLINE_LIMIT}
 CFLAGS.gcc+= --param inline-unit-growth=${CFLAGS_PARAM_INLINE_UNIT_GROWTH}
 CFLAGS.gcc+= --param large-function-growth=${CFLAGS_PARAM_LARGE_FUNCTION_GROWTH}
-CFLAGS.gcc+= -fms-extensions
 .if defined(CFLAGS_ARCH_PARAMS)
 CFLAGS.gcc+=${CFLAGS_ARCH_PARAMS}
 .endif
diff --git a/sys/conf/kmod.mk b/sys/conf/kmod.mk
index aacd7a17ef9..c35116dfcaa 100644
--- a/sys/conf/kmod.mk
+++ b/sys/conf/kmod.mk
@@ -139,7 +139,6 @@ CFLAGS+=	-include ${.OBJDIR}/opt_global.h
 CFLAGS+=	-I. -I${SYSDIR} -I${SYSDIR}/contrib/ck/include
 
 CFLAGS.gcc+=	-finline-limit=${INLINE_LIMIT}
-CFLAGS.gcc+=	-fms-extensions
 CFLAGS.gcc+= --param inline-unit-growth=100
 CFLAGS.gcc+= --param large-function-growth=1000
 
diff --git a/sys/modules/iser/Makefile b/sys/modules/iser/Makefile
index ff08ae6f346..2c00b3a4027 100644
--- a/sys/modules/iser/Makefile
+++ b/sys/modules/iser/Makefile
@@ -17,7 +17,6 @@ CFLAGS+= -I${SYSDIR}/ofed/include/uapi
 CFLAGS+= ${LINUXKPI_INCLUDES}
 CFLAGS+= -DCONFIG_INFINIBAND_USER_MEM
 CFLAGS+= -DINET6 -DINET
-CFLAGS+= -fms-extensions
 
 CFLAGS+=-DICL_KERNEL_PROXY
 
diff --git a/sys/modules/pms/Makefile b/sys/modules/pms/Makefile
index 8bd21fc4b50..81599e0a3ce 100644
--- a/sys/modules/pms/Makefile
+++ b/sys/modules/pms/Makefile
@@ -17,7 +17,6 @@
 	${SRCTOP}/sys/dev/pms/freebsd/driver/common
 
 CFLAGS+=-fno-builtin
-CFLAGS+=-fms-extensions
 
 CFLAGS+=-Wredundant-decls
 CFLAGS+=-Wunused-variable
diff --git a/sys/powerpc/conf/dpaa/config.dpaa b/sys/powerpc/conf/dpaa/config.dpaa
index 6a923baed89..0b7c8fcf3b2 100644
--- a/sys/powerpc/conf/dpaa/config.dpaa
+++ b/sys/powerpc/conf/dpaa/config.dpaa
@@ -2,7 +2,7 @@
 files		"dpaa/files.dpaa"
 
 makeoptions DPAA_COMPILE_CMD="${LINUXKPI_C} ${DPAAWARNFLAGS} \
-	-Wno-cast-qual -Wno-unused-function -Wno-init-self -fms-extensions \
+	-Wno-cast-qual -Wno-unused-function -Wno-init-self \
 	-include $S/contrib/ncsw/build/dflags.h \
 	-Wno-error=missing-prototypes \
 	-I$S/contrib/ncsw/build/ \