Index: lib/libc/regex/engine.c
===================================================================
--- lib/libc/regex/engine.c
+++ lib/libc/regex/engine.c
@@ -789,7 +789,7 @@
 	ASSIGN(fresh, st);
 	SP("start", st, *p);
 	coldp = NULL;
-	if (start == m->beginp)
+	if (start == m->offp)
 		c = OUT;
 	else {
 		/*
@@ -894,7 +894,7 @@
 	SP("sstart", st, *p);
 	st = step(m->g, startst, stopst, st, NOTHING, st);
 	matchp = NULL;
-	if (start == m->beginp)
+	if (start == m->offp)
 		c = OUT;
 	else {
 		/*
Index: lib/libc/regex/regcomp.c
===================================================================
--- lib/libc/regex/regcomp.c
+++ lib/libc/regex/regcomp.c
@@ -768,8 +768,10 @@
 	char c;
 	wint_t start, finish;
 	wint_t i;
+#ifndef REDEBUG
 	struct xlocale_collate *table =
 		(struct xlocale_collate*)__get_locale()->components[XLC_COLLATE];
+#endif
 
 	/* classify what we've got */
 	switch ((MORE()) ? PEEK() : '\0') {
@@ -817,9 +819,12 @@
 		if (start == finish)
 			CHadd(p, cs, start);
 		else {
+#ifndef REDEBUG
 			if (table->__collate_load_error) {
+#endif
 				(void)REQUIRE((uch)start <= (uch)finish, REG_ERANGE);
 				CHaddrange(p, cs, start, finish);
+#ifndef REDEBUG
 			} else {
 				(void)REQUIRE(__collate_range_cmp(table, start, finish) <= 0, REG_ERANGE);
 				for (i = 0; i <= UCHAR_MAX; i++) {
@@ -829,6 +834,7 @@
 						CHadd(p, cs, i);
 				}
 			}
+#endif
 		}
 		break;
 	}
Index: usr.bin/sed/process.c
===================================================================
--- usr.bin/sed/process.c
+++ usr.bin/sed/process.c
@@ -71,7 +71,7 @@
 static void		 do_tr(struct s_tr *);
 static void		 flush_appends(void);
 static void		 lputs(char *, size_t);
-static int		 regexec_e(regex_t *, const char *, int, int, size_t);
+static int		 regexec_e(regex_t *, const char *, int, int, const char *, size_t);
 static void		 regsub(SPACE *, char *, char *);
 static int		 substitute(struct s_command *);
 
@@ -281,7 +281,7 @@
  * (lastline, linenumber, ps).
  */
 #define	MATCH(a)							\
-	((a)->type == AT_RE ? regexec_e((a)->u.r, ps, 0, 1, psl) :	\
+	((a)->type == AT_RE ? regexec_e((a)->u.r, ps, 0, 1, ps, psl) :	\
 	    (a)->type == AT_LINE ? linenum == (a)->u.l : lastline())
 
 /*
@@ -392,7 +392,7 @@
 					linenum, fname, cp->u.s->maxbref);
 		}
 	}
-	if (!regexec_e(re, s, 0, 0, psl))
+	if (!regexec_e(re, s, 0, 0, s, psl))
 		return (0);
 
 	SS.len = 0;				/* Clean substitute space. */
@@ -407,25 +407,25 @@
 				/* Locate start of replaced string. */
 				re_off = match[0].rm_so;
 				/* Copy leading retained string. */
-				cspace(&SS, s, re_off, APPEND);
+				cspace(&SS, s, re_off - (s - ps), APPEND);
 				/* Add in regular expression. */
-				regsub(&SS, s, cp->u.s->new);
+				regsub(&SS, ps, cp->u.s->new);
 			}
 
 			/* Move past this match. */
 			if (match[0].rm_so != match[0].rm_eo) {
-				s += match[0].rm_eo;
-				slen -= match[0].rm_eo;
+				s = ps + match[0].rm_eo;
+				slen = psl - match[0].rm_eo;
 				lastempty = 0;
 			} else {
-				if (match[0].rm_so < slen)
-					cspace(&SS, s + match[0].rm_so, 1,
+				if (match[0].rm_so < psl)
+					cspace(&SS, ps + match[0].rm_so, 1,
 					    APPEND);
-				s += match[0].rm_so + 1;
-				slen -= match[0].rm_so + 1;
+				s = ps + match[0].rm_so + 1;
+				slen = psl - match[0].rm_so - 1;
 				lastempty = 1;
 			}
-		} while (slen >= 0 && regexec_e(re, s, REG_NOTBOL, 0, slen));
+		} while (slen >= 0 && regexec_e(re, ps, REG_NOTBOL, 0, s, slen));
 		/* Copy trailing retained string. */
 		if (slen > 0)
 			cspace(&SS, s, slen, APPEND);
@@ -434,24 +434,24 @@
 		while (--n) {
 			if (match[0].rm_eo == match[0].rm_so)
 				match[0].rm_eo = match[0].rm_so + 1;
-			s += match[0].rm_eo;
-			slen -= match[0].rm_eo;
+			s = ps + match[0].rm_eo;
+			slen = psl - match[0].rm_eo;
 			if (slen < 0)
 				return (0);
-			if (!regexec_e(re, s, REG_NOTBOL, 0, slen))
+			if (!regexec_e(re, ps, REG_NOTBOL, 0, s, slen))
 				return (0);
 		}
 		/* FALLTHROUGH */
 	case 1:					/* 1st occurrence */
 		/* Locate start of replaced string. */
-		re_off = match[0].rm_so + (s - ps);
+		re_off = match[0].rm_so;
 		/* Copy leading retained string. */
 		cspace(&SS, ps, re_off, APPEND);
 		/* Add in regular expression. */
-		regsub(&SS, s, cp->u.s->new);
+		regsub(&SS, ps, cp->u.s->new);
 		/* Copy trailing retained string. */
-		s += match[0].rm_eo;
-		slen -= match[0].rm_eo;
+		s = ps + match[0].rm_eo;
+		slen = psl - match[0].rm_eo;
 		cspace(&SS, s, slen, APPEND);
 		break;
 	}
@@ -658,7 +658,7 @@
 
 static int
 regexec_e(regex_t *preg, const char *string, int eflags, int nomatch,
-	size_t slen)
+	const char *start, size_t slen)
 {
 	int eval;
 
@@ -669,8 +669,8 @@
 		defpreg = preg;
 
 	/* Set anchors */
-	match[0].rm_so = 0;
-	match[0].rm_eo = slen;
+	match[0].rm_so = start - string;
+	match[0].rm_eo = match[0].rm_so + slen;
 
 	eval = regexec(defpreg, string,
 	    nomatch ? 0 : maxnsub + 1, match, eflags | REG_STARTEND);