diff --git a/share/mk/bsd.mkopt.mk b/share/mk/bsd.mkopt.mk
index 9cfe1bf09d0..f0d9add7547 100644
--- a/share/mk/bsd.mkopt.mk
+++ b/share/mk/bsd.mkopt.mk
@@ -18,6 +18,10 @@
 # after all this processing, allowing this file to be included
 # multiple times with different lists.
 #
+# Other parts of the build system will set BROKEN_OPTIONS to a list
+# of options that are broken on this platform. This will not be unset
+# before returning. Clients are expected to always += this variable.
+#
 # Users should generally define WITH_FOO or WITHOUT_FOO, but the build
 # system should use MK_FOO={yes,no} when it needs to override the
 # user's desires or default behavior.
@@ -58,3 +62,11 @@ MK_${var}:=	no
 .endif # !defined(MK_${var})
 .endfor
 .undef __DEFAULT_NO_OPTIONS
+
+#
+# MK_* options which are always no, usually because they are
+# unsupported/badly broken on this architecture.
+#
+.for var in ${BROKEN_OPTIONS}
+MK_${var}:=	no
+.endfor
diff --git a/sys/conf/kern.opts.mk b/sys/conf/kern.opts.mk
index 112c217e2da..0e9ec7e5d6c 100644
--- a/sys/conf/kern.opts.mk
+++ b/sys/conf/kern.opts.mk
@@ -82,6 +82,16 @@ MK_${var}:=	no
 .endfor
 .undef __DEFAULT_NO_OPTIONS
 
+#
+# MK_* options which are always no, usually because they are
+# unsupported/badly broken on this architecture.
+#
+.for var in ${BROKEN_OPTIONS}
+MK_${var}:=	no
+.endfor
+.undef BROKEN_OPTIONS
+#end of bsd.mkopt.mk expanded inline.
+
 #
 # MK_*_SUPPORT options which default to "yes" unless their corresponding
 # MK_* variable is set to "no".
@@ -104,6 +114,3 @@ MK_${var}_SUPPORT:= yes
 .endif
 .endif
 .endfor
-
-
-