diff --git a/lib/Makefile b/lib/Makefile
index 8352329b7a5..2607d5d6ab5 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -160,6 +160,7 @@ _libcplusplus=	libc++
 .endif
 
 SUBDIR.${MK_EFI}+=	libefivar
+SUBDIR.${MK_LIBREGEX}+=	libregex
 SUBDIR.${MK_LIBTHR}+=	libthr
 SUBDIR.${MK_LLVM_LIBUNWIND}+=	libgcc_eh
 SUBDIR.${MK_LLVM_LIBUNWIND}+=	libgcc_s
diff --git a/lib/libc/regex/Makefile.inc b/lib/libc/regex/Makefile.inc
index 4595361b281..5a73c90f5ad 100644
--- a/lib/libc/regex/Makefile.inc
+++ b/lib/libc/regex/Makefile.inc
@@ -2,7 +2,7 @@
 # $FreeBSD$
 
 # regex sources
-.PATH: ${LIBC_SRCTOP}/regex
+.PATH: ${SRCTOP}/lib/libc/regex
 
 CFLAGS+=-DPOSIX_MISTAKE
 
@@ -10,8 +10,11 @@ SRCS+=	regcomp.c regerror.c regexec.c regfree.c
 
 SYM_MAPS+=${LIBC_SRCTOP}/regex/Symbol.map
 
+# manpages only included in libc version
+.if ${LIB} == "c"
 MAN+=	regex.3
 MAN+=	re_format.7
 
 MLINKS+=regex.3 regcomp.3 regex.3 regexec.3 regex.3 regerror.3
 MLINKS+=regexec.3 regfree.3
+.endif
diff --git a/lib/libc/regex/cname.h b/lib/libc/regex/cname.h
index ba7dd8cb964..28452c93fe7 100644
--- a/lib/libc/regex/cname.h
+++ b/lib/libc/regex/cname.h
@@ -36,7 +36,7 @@
 
 /* character-name table */
 static struct cname {
-	char *name;
+	const char *name;
 	char code;
 } cnames[] = {
 	{"NUL",			'\0'},
diff --git a/lib/libc/regex/engine.c b/lib/libc/regex/engine.c
index 073e0010882..95c04b712ab 100644
--- a/lib/libc/regex/engine.c
+++ b/lib/libc/regex/engine.c
@@ -680,7 +680,7 @@ backref(struct match *m,
 		ssp = m->offp + m->pmatch[i].rm_so;
 		if (memcmp(sp, ssp, len) != 0)
 			return(NULL);
-		while (m->g->strip[ss] != SOP(O_BACK, i))
+		while (m->g->strip[ss] != (sop)SOP(O_BACK, i))
 			ss++;
 		return(backref(m, sp+len, stop, ss+1, stopst, lev, rec));
 	case OQUEST_:		/* to null or not */
@@ -841,7 +841,7 @@ fast(	struct match *m,
 		}
 
 		/* are we done? */
-		if (ISSET(st, stopst) || p == stop || clen > stop - p)
+		if (ISSET(st, stopst) || p == stop || clen > (size_t)(stop - p))
 			break;		/* NOTE BREAK OUT */
 
 		/* no, we must deal with this character */
@@ -946,7 +946,7 @@ slow(	struct match *m,
 		/* are we done? */
 		if (ISSET(st, stopst))
 			matchp = p;
-		if (EQ(st, empty) || p == stop || clen > stop - p)
+		if (EQ(st, empty) || p == stop || clen > (size_t)(stop - p))
 			break;		/* NOTE BREAK OUT */
 
 		/* no, we must deal with this character */
diff --git a/lib/libc/regex/regcomp.c b/lib/libc/regex/regcomp.c
index 95764717bda..63966b0d9ce 100644
--- a/lib/libc/regex/regcomp.c
+++ b/lib/libc/regex/regcomp.c
@@ -54,7 +54,9 @@ __FBSDID("$FreeBSD$");
 #include <wchar.h>
 #include <wctype.h>
 
+#ifndef LIBREGEX_BUILD
 #include "collate.h"
+#endif
 
 #include "utils.h"
 #include "regex2.h"
@@ -92,6 +94,7 @@ static void p_bre(struct parse *p, int end1, int end2);
 static int p_simp_re(struct parse *p, int starordinary);
 static int p_count(struct parse *p);
 static void p_bracket(struct parse *p);
+static int p_range_cmp(wchar_t c1, wchar_t c2);
 static void p_b_term(struct parse *p, cset *cs);
 static void p_b_cclass(struct parse *p, cset *cs);
 static void p_b_eclass(struct parse *p, cset *cs);
@@ -207,7 +210,7 @@ regcomp(regex_t * __restrict preg,
 			return(REG_INVARG);
 		len = preg->re_endp - pattern;
 	} else
-		len = strlen((char *)pattern);
+		len = strlen(pattern);
 
 	/* do the mallocs early so failure handling is easy */
 	g = (struct re_guts *)malloc(sizeof(struct re_guts));
@@ -239,7 +242,7 @@ regcomp(regex_t * __restrict preg,
 
 	/* set things up */
 	p->g = g;
-	p->next = (char *)pattern;	/* convenience; we do not modify it */
+	p->next = __DECONST(char *, pattern);	/* convenience; we do not modify it */
 	p->end = p->next + len;
 	p->error = 0;
 	p->ncsalloc = 0;
@@ -757,6 +760,23 @@ p_bracket(struct parse *p)
 		EMIT(OANYOF, (int)(cs - p->g->sets));
 }
 
+static int
+p_range_cmp(wchar_t c1, wchar_t c2)
+{
+#ifndef LIBREGEX_BUILD
+	return __wcollate_range_cmp(c1, c2);
+#else
+	/* Copied from libc/collate __wcollate_range_cmp */
+	wchar_t s1[2], s2[2];
+
+	s1[0] = c1;
+	s1[1] = L'\0';
+	s2[0] = c2;
+	s2[1] = L'\0';
+	return (wcscoll(s1, s2));
+#endif
+}
+
 /*
  - p_b_term - parse one term of a bracketed character list
  == static void p_b_term(struct parse *p, cset *cs);
@@ -767,9 +787,10 @@ p_b_term(struct parse *p, cset *cs)
 	char c;
 	wint_t start, finish;
 	wint_t i;
+#ifndef LIBREGEX_BUILD
 	struct xlocale_collate *table =
 		(struct xlocale_collate*)__get_locale()->components[XLC_COLLATE];
-
+#endif
 	/* classify what we've got */
 	switch ((MORE()) ? PEEK() : '\0') {
 	case '[':
@@ -816,15 +837,18 @@ p_b_term(struct parse *p, cset *cs)
 		if (start == finish)
 			CHadd(p, cs, start);
 		else {
+#ifndef LIBREGEX_BUILD
 			if (table->__collate_load_error || MB_CUR_MAX > 1) {
+#else
+			if (MB_CUR_MAX > 1) {
+#endif
 				(void)REQUIRE(start <= finish, REG_ERANGE);
 				CHaddrange(p, cs, start, finish);
 			} else {
-				(void)REQUIRE(__wcollate_range_cmp(start, finish) <= 0, REG_ERANGE);
+				(void)REQUIRE(p_range_cmp(start, finish) <= 0, REG_ERANGE);
 				for (i = 0; i <= UCHAR_MAX; i++) {
-					if (   __wcollate_range_cmp(start, i) <= 0
-					    && __wcollate_range_cmp(i, finish) <= 0
-					   )
+					if (p_range_cmp(start, i) <= 0 &&
+					    p_range_cmp(i, finish) <= 0 )
 						CHadd(p, cs, i);
 				}
 			}
@@ -905,7 +929,7 @@ p_b_coll_elem(struct parse *p,
 {
 	char *sp = p->next;
 	struct cname *cp;
-	int len;
+	size_t len;
 	mbstate_t mbs;
 	wchar_t wc;
 	size_t clen;
diff --git a/lib/libc/regex/regerror.c b/lib/libc/regex/regerror.c
index 253f0b1fb71..8496ba78002 100644
--- a/lib/libc/regex/regerror.c
+++ b/lib/libc/regex/regerror.c
@@ -54,7 +54,7 @@ extern "C" {
 #endif
 
 /* === regerror.c === */
-static char *regatoi(const regex_t *preg, char *localbuf);
+static const char *regatoi(const regex_t *preg, char *localbuf);
 
 #ifdef __cplusplus
 }
@@ -83,8 +83,8 @@ static char *regatoi(const regex_t *preg, char *localbuf);
  */
 static struct rerr {
 	int code;
-	char *name;
-	char *explain;
+	const char *name;
+	const char *explain;
 } rerrs[] = {
 	{REG_NOMATCH,	"REG_NOMATCH",	"regexec() failed to match"},
 	{REG_BADPAT,	"REG_BADPAT",	"invalid regular expression"},
@@ -120,7 +120,7 @@ regerror(int errcode,
 	struct rerr *r;
 	size_t len;
 	int target = errcode &~ REG_ITOA;
-	char *s;
+	const char *s;
 	char convbuf[50];
 
 	if (errcode == REG_ATOI)
@@ -158,7 +158,7 @@ regerror(int errcode,
  - regatoi - internal routine to implement REG_ATOI
  == static char *regatoi(const regex_t *preg, char *localbuf);
  */
-static char *
+static const char *
 regatoi(const regex_t *preg, char *localbuf)
 {
 	struct rerr *r;
diff --git a/lib/libc/regex/regexec.c b/lib/libc/regex/regexec.c
index 0edfe43dbab..cf141069aa8 100644
--- a/lib/libc/regex/regexec.c
+++ b/lib/libc/regex/regexec.c
@@ -225,9 +225,9 @@ regexec(const regex_t * __restrict preg,
 	eflags = GOODFLAGS(eflags);
 
 	if (MB_CUR_MAX > 1)
-		return(mmatcher(g, (char *)string, nmatch, pmatch, eflags));
-	else if (g->nstates <= CHAR_BIT*sizeof(states1) && !(eflags&REG_LARGE))
-		return(smatcher(g, (char *)string, nmatch, pmatch, eflags));
+		return(mmatcher(g, string, nmatch, pmatch, eflags));
+	else if (g->nstates <= (sopno)(CHAR_BIT*sizeof(states1)) && !(eflags&REG_LARGE))
+		return(smatcher(g, string, nmatch, pmatch, eflags));
 	else
-		return(lmatcher(g, (char *)string, nmatch, pmatch, eflags));
+		return(lmatcher(g, string, nmatch, pmatch, eflags));
 }
diff --git a/lib/libregex/Makefile b/lib/libregex/Makefile
new file mode 100644
index 00000000000..12b559a6534
--- /dev/null
+++ b/lib/libregex/Makefile
@@ -0,0 +1,10 @@
+# $FreeBSD$
+
+PACKAGE=lib${LIB}
+LIB=	regex
+
+CFLAGS+=	-DLIBREGEX_BUILD
+SYMBOL_MAPS=	${SYM_MAPS}
+
+.include "${SRCTOP}/lib/libc/regex/Makefile.inc"
+.include <bsd.lib.mk>
diff --git a/share/mk/src.opts.mk b/share/mk/src.opts.mk
index 86485557b70..5d07a47b30f 100644
--- a/share/mk/src.opts.mk
+++ b/share/mk/src.opts.mk
@@ -122,6 +122,7 @@ __DEFAULT_YES_OPTIONS = \
     LEGACY_CONSOLE \
     LIB32 \
     LIBPTHREAD \
+    LIBREGEX \
     LIBTHR \
     LOCALES \
     LOCATE \
diff --git a/tools/build/options/WITHOUT_LIBREGEX b/tools/build/options/WITHOUT_LIBREGEX
new file mode 100644
index 00000000000..7206749a0d4
--- /dev/null
+++ b/tools/build/options/WITHOUT_LIBREGEX
@@ -0,0 +1,4 @@
+.\" $FreeBSD$
+Set to not build the
+.Nm libregex
+library for GNU regex(3) extensions.