diff --git a/share/mk/bsd.mkopt.mk b/share/mk/bsd.mkopt.mk
--- a/share/mk/bsd.mkopt.mk
+++ b/share/mk/bsd.mkopt.mk
@@ -8,6 +8,8 @@
 # "yes", unless WITHOUT_FOO is defined, in which case it is set to
 # "no".
 #
+# For each option FOO in __REQUIRED_OPTIONS, MK_FOO is set to "yes".
+#
 # For each option FOO in __DEFAULT_NO_OPTIONS, MK_FOO is set to "no",
 # unless WITH_FOO is defined, in which case it is set to "yes".
 #
@@ -52,6 +54,14 @@
 .endfor
 .undef __DEFAULT_YES_OPTIONS
 
+#
+# MK_* options which are always yes, typically as a transitional
+# step towards removing the options entirely.
+#
+.for var in ${__REQUIRED_OPTIONS}
+MK_${var}:=	yes
+.endfor
+
 #
 # MK_* options which default to "no".
 #
diff --git a/share/mk/src.opts.mk b/share/mk/src.opts.mk
--- a/share/mk/src.opts.mk
+++ b/share/mk/src.opts.mk
@@ -53,6 +53,9 @@
 # BROKEN was selected as the least imperfect one considered at the
 # time. Options are added to BROKEN_OPTIONS list on a per-arch basis.
 # At this time, there's no provision for mutually incompatible options.
+# Options listed in 'REQUIRED_OPTIONS' will be hard-wired to 'yes'; this
+# is intended as a transitional measure while options are in the process
+# of being removed.
 
 __DEFAULT_YES_OPTIONS = \
     ACCT \
@@ -213,6 +216,8 @@
     SORT_THREADS \
     ZONEINFO_LEAPSECONDS_SUPPORT \
 
+__REQUIRED_OPTIONS = \
+
 # LEFT/RIGHT. Left options which default to "yes" unless their corresponding
 # RIGHT option is disabled.
 __DEFAULT_DEPENDENT_OPTIONS= \