Index: lib/libc/regex/regex.3
===================================================================
--- lib/libc/regex/regex.3	(revision 286580)
+++ lib/libc/regex/regex.3	(working copy)
@@ -723,5 +723,3 @@
 .Pp
 The implementation of word-boundary matching is a bit of a kludge,
 and bugs may lurk in combinations of word-boundary matching and anchoring.
-.Pp
-Word-boundary matching does not work properly in multibyte locales.
Index: lib/libc/regex/regexec.c
===================================================================
--- lib/libc/regex/regexec.c	(revision 286580)
+++ lib/libc/regex/regexec.c	(working copy)
@@ -116,9 +116,9 @@
 #define	FWD(dst, src, n)	((dst) |= ((unsigned long)(src)&(here)) << (n))
 #define	BACK(dst, src, n)	((dst) |= ((unsigned long)(src)&(here)) >> (n))
 #define	ISSETBACK(v, n)	(((v) & ((unsigned long)here >> (n))) != 0)
-/* no multibyte support */
-#define	XMBRTOWC	xmbrtowc_dummy
-#define	ZAPSTATE(mbs)	((void)(mbs))
+/* multibyte support */
+#define	XMBRTOWC	xmbrtowc
+#define	ZAPSTATE(mbs)	memset((mbs), 0, sizeof(*(mbs)))
 /* function names */
 #define SNAMES			/* engine.c looks after details */
 
@@ -170,9 +170,9 @@
 #define	FWD(dst, src, n)	((dst)[here+(n)] |= (src)[here])
 #define	BACK(dst, src, n)	((dst)[here-(n)] |= (src)[here])
 #define	ISSETBACK(v, n)	((v)[here - (n)])
-/* no multibyte support */
-#define	XMBRTOWC	xmbrtowc_dummy
-#define	ZAPSTATE(mbs)	((void)(mbs))
+/* multibyte support */
+#define	XMBRTOWC	xmbrtowc
+#define	ZAPSTATE(mbs)	memset((mbs), 0, sizeof(*(mbs)))
 /* function names */
 #define	LNAMES			/* flag */