Index: head/share/man/man5/src.conf.5
===================================================================
--- head/share/man/man5/src.conf.5
+++ head/share/man/man5/src.conf.5
@@ -1,6 +1,6 @@
 .\" DO NOT EDIT-- this file is generated by tools/build/options/makeman.
 .\" $FreeBSD$
-.Dd April 19, 2017
+.Dd April 21, 2017
 .Dt SRC.CONF 5
 .Os
 .Sh NAME
@@ -215,6 +215,11 @@
 .Xr libarchive 3 .
 .It Va WITH_BSD_GREP
 Install BSD-licensed grep as '[ef]grep' instead of GNU grep.
+.It Va WITHOUT_BSD_GREP_FASTMATCH
+Set this option to exclude the fastmatch implementation from
+.Xr bsdgrep 1 ,
+instead using only
+.Xr regex 3 .
 .It Va WITHOUT_BSNMP
 Set to not build or install
 .Xr bsnmpd 1
Index: head/share/mk/src.opts.mk
===================================================================
--- head/share/mk/src.opts.mk
+++ head/share/mk/src.opts.mk
@@ -62,6 +62,7 @@
     BOOTPARAMD \
     BOOTPD \
     BSD_CPIO \
+    BSD_GREP_FASTMATCH \
     BSDINSTALL \
     BSNMP \
     BZIP2 \
Index: head/tools/build/options/WITHOUT_BSD_GREP_FASTMATCH
===================================================================
--- head/tools/build/options/WITHOUT_BSD_GREP_FASTMATCH
+++ head/tools/build/options/WITHOUT_BSD_GREP_FASTMATCH
@@ -0,0 +1,5 @@
+.\" $FreeBSD$
+Set this option to exclude the fastmatch implementation from
+.Xr bsdgrep 1 ,
+instead using only
+.Xr regex 3 .
Index: head/usr.bin/grep/Makefile
===================================================================
--- head/usr.bin/grep/Makefile
+++ head/usr.bin/grep/Makefile
@@ -15,10 +15,14 @@
 .endif
 SRCS=	file.c grep.c queue.c util.c
 
-# Extra files ported backported form some regex improvements
+.if ${MK_BSD_GREP_FASTMATCH} == "yes"
+# Extra files ported backported for some regex improvements
 .PATH: ${.CURDIR}/regex
 SRCS+=	fastmatch.c hashtable.c tre-compile.c tre-fastmatch.c
 CFLAGS+=-I${.CURDIR}/regex
+.else
+CFLAGS+= -DWITHOUT_FASTMATCH
+.endif
 
 CFLAGS.gcc+= --param max-inline-insns-single=500
 
Index: head/usr.bin/grep/grep.h
===================================================================
--- head/usr.bin/grep/grep.h
+++ head/usr.bin/grep/grep.h
@@ -36,7 +36,9 @@
 #include <stdio.h>
 #include <zlib.h>
 
+#ifndef WITHOUT_FASTMATCH
 #include "fastmatch.h"
+#endif
 
 #ifdef WITHOUT_NLS
 #define	getstr(n)	 errstr[n]
@@ -127,7 +129,9 @@
 extern struct pat *pattern;
 extern struct epat *dpattern, *fpattern;
 extern regex_t	*er_pattern, *r_pattern;
+#ifndef WITHOUT_FASTMATCH
 extern fastmatch_t *fg_pattern;
+#endif
 
 /* For regex errors  */
 #define	RE_ERROR_BUF	512
Index: head/usr.bin/grep/grep.c
===================================================================
--- head/usr.bin/grep/grep.c
+++ head/usr.bin/grep/grep.c
@@ -49,7 +49,9 @@
 #include <string.h>
 #include <unistd.h>
 
+#ifndef WITHOUT_FASTMATCH
 #include "fastmatch.h"
+#endif
 #include "grep.h"
 
 #ifndef WITHOUT_NLS
@@ -86,7 +88,9 @@
 static unsigned int pattern_sz;
 struct pat	*pattern;
 regex_t		*r_pattern;
+#ifndef WITHOUT_FASTMATCH
 fastmatch_t	*fg_pattern;
+#endif
 
 /* Filename exclusion/inclusion patterns */
 unsigned int	fpatterns, dpatterns;
@@ -715,20 +719,25 @@
 		usage();
 	}
 
+#ifndef WITHOUT_FASTMATCH
 	fg_pattern = grep_calloc(patterns, sizeof(*fg_pattern));
+#endif
 	r_pattern = grep_calloc(patterns, sizeof(*r_pattern));
 
 	/* Check if cheating is allowed (always is for fgrep). */
 	for (i = 0; i < patterns; ++i) {
+#ifndef WITHOUT_FASTMATCH
+		/* Attempt compilation with fastmatch regex and fallback to
+		   regex(3) if it fails. */
 		if (fastncomp(&fg_pattern[i], pattern[i].pat,
-		    pattern[i].len, cflags) != 0) {
-			/* Fall back to full regex library */
-			c = regcomp(&r_pattern[i], pattern[i].pat, cflags);
-			if (c != 0) {
-				regerror(c, &r_pattern[i], re_error,
-				    RE_ERROR_BUF);
-				errx(2, "%s", re_error);
-			}
+		    pattern[i].len, cflags) == 0)
+			continue;
+#endif
+		c = regcomp(&r_pattern[i], pattern[i].pat, cflags);
+		if (c != 0) {
+			regerror(c, &r_pattern[i], re_error,
+			    RE_ERROR_BUF);
+			errx(2, "%s", re_error);
 		}
 	}
 
Index: head/usr.bin/grep/util.c
===================================================================
--- head/usr.bin/grep/util.c
+++ head/usr.bin/grep/util.c
@@ -49,7 +49,9 @@
 #include <wchar.h>
 #include <wctype.h>
 
+#ifndef WITHOUT_FASTMATCH
 #include "fastmatch.h"
+#endif
 #include "grep.h"
 
 static int	 linesqueued;
@@ -317,10 +319,12 @@
 		for (i = 0; i < patterns; i++) {
 			pmatch.rm_so = st;
 			pmatch.rm_eo = l->len;
+#ifndef WITHOUT_FASTMATCH
 			if (fg_pattern[i].pattern)
 				r = fastexec(&fg_pattern[i],
 				    l->dat, 1, &pmatch, leflags);
 			else
+#endif
 				r = regexec(&r_pattern[i], l->dat, 1,
 				    &pmatch, leflags);
 			r = (r == 0) ? 0 : REG_NOMATCH;
@@ -332,7 +336,11 @@
 				    (size_t)pmatch.rm_eo != l->len)
 					r = REG_NOMATCH;
 			/* Check for whole word match */
+#ifndef WITHOUT_FASTMATCH
 			if (r == 0 && (wflag || fg_pattern[i].word)) {
+#else
+			if (r == 0 && wflag) {
+#endif
 				wchar_t wbegin, wend;
 
 				wbegin = wend = L' ';