Index: libc/usr/src/common/util/qsort.c
===================================================================
--- libc.orig/usr/src/common/util/qsort.c
+++ libc/usr/src/common/util/qsort.c
@@ -50,9 +50,15 @@ static void swapb(char *r1, char *r2, si
  * note: cstyle specifically prohibits nested conditional operators
  * but this is the only way to do the median of 3 function in-line
  */
+#ifdef QSORT_R
+#define	med3(a, b, c) (cmp((a), (b), arg) < 0) \
+	? ((cmp((b), (c), arg) < 0) ? (b) : (cmp((a), (c), arg) < 0) ? (c) : (a)) \
+	: ((cmp((b), (c), arg) > 0) ? (b) : (cmp((a), (c), arg) > 0) ? (c) : (a))
+#else
 #define	med3(a, b, c) (cmp((a), (b)) < 0) \
 	? ((cmp((b), (c)) < 0) ? (b) : (cmp((a), (c)) < 0) ? (c) : (a)) \
 	: ((cmp((b), (c)) > 0) ? (b) : (cmp((a), (c)) > 0) ? (c) : (a))
+#endif
 
 #define	THRESH_L	5	/* threshold for insertion sort */
 #define	THRESH_M3	20	/* threshold for median of 3 */
@@ -104,12 +110,22 @@ typedef struct {
  *   9) The user compare function modifies the data records
  */
 
+#ifdef QSORT_R
+void
+qsort_r(
+	void		*basep,
+	size_t		nrec,
+	size_t		rsiz,
+	int		(*cmp)(const void *, const void *, void *),
+    void *arg)
+#else
 void
 qsort(
 	void		*basep,
 	size_t		nrec,
 	size_t		rsiz,
 	int		(*cmp)(const void *, const void *))
+#endif
 {
 	size_t		i;		/* temporary variable */
 
@@ -209,7 +225,12 @@ qsort(
 				b_par = t_par;
 				while (b_par > b_lim) {
 					b_par -= rsiz;
-					if ((*cmp)(b_par, b_par + rsiz) <= 0) {
+#ifdef QSORT_R
+					if ((*cmp)(b_par, b_par + rsiz, arg) <= 0)
+#else
+					if ((*cmp)(b_par, b_par + rsiz) <= 0)
+#endif
+                    {
 						break;
 					}
 					(*swapf)(b_par, b_par + rsiz, loops);
@@ -323,7 +344,11 @@ qsort(
 				if (b_par == m2) {
 					continue;
 				}
+#ifdef QSORT_R
+				cv = cmp(b_par, m2, arg);
+#else
 				cv = cmp(b_par, m2);
+#endif
 				if (cv > 0) {
 					break;
 				}
@@ -342,7 +367,11 @@ qsort(
 				if (t_par == m2) {
 					continue;
 				}
+#ifdef QSORT_R
+				cv = cmp(t_par, m2, arg);
+#else
 				cv = cmp(t_par, m2);
+#endif
 				if (cv < 0) {
 					break;
 				}
Index: libc/usr/src/lib/libc/port/mapfile-vers
===================================================================
--- libc.orig/usr/src/lib/libc/port/mapfile-vers
+++ libc/usr/src/lib/libc/port/mapfile-vers
@@ -289,6 +289,7 @@ SYMBOL_VERSION DYSON_1 {
         memrchr;
         program_invocation_name;
         program_invocation_short_name;
+        qsort_r;
         rawmemchr;
         sendfile;
         sendfilev;
Index: libc/usr/src/lib/libc/i386/Makefile.com
===================================================================
--- libc.orig/usr/src/lib/libc/i386/Makefile.com
+++ libc/usr/src/lib/libc/i386/Makefile.com
@@ -101,6 +101,7 @@ COMOBJS=			\
 	bsearch.o		\
 	bzero.o			\
 	qsort.o			\
+	qsort_r.o		\
 	strtol.o		\
 	strtoul.o		\
 	strtoll.o		\
Index: libc/usr/src/common/util/qsort_r.c
===================================================================
--- /dev/null
+++ libc/usr/src/common/util/qsort_r.c
@@ -0,0 +1,2 @@
+#define QSORT_R
+#include "qsort.c"
Index: libc/usr/src/lib/libc/amd64/Makefile
===================================================================
--- libc.orig/usr/src/lib/libc/amd64/Makefile
+++ libc/usr/src/lib/libc/amd64/Makefile
@@ -100,6 +100,7 @@ COMOBJS=			\
 	bsearch.o		\
 	bzero.o			\
 	qsort.o			\
+	qsort_r.o		\
 	strtol.o		\
 	strtoul.o		\
 	strtoll.o		\
Index: libc/usr/src/head/stdlib.h
===================================================================
--- libc.orig/usr/src/head/stdlib.h
+++ libc/usr/src/head/stdlib.h
@@ -34,6 +34,8 @@
 #ifndef _STDLIB_H
 #define	_STDLIB_H
 
+#include <features.h>
+
 #include <iso/stdlib_iso.h>
 #include <iso/stdlib_c99.h>
 
@@ -43,7 +45,17 @@
 
 #if defined(_GNU_SOURCE) || defined(__EXTENSIONS__)
 # include <alloca.h>
+
+#if __cplusplus >= 199711L
+namespace std {
 #endif
+void qsort_r(void *, size_t, size_t, int (*)(const void *, const void *, void *), void *);
+
+#if __cplusplus >= 199711L
+}
+#endif /* end of namespace std */
+
+#endif /* _GNU_SOURCE */
 
 
 /*
@@ -73,6 +85,9 @@ using std::mblen;
 using std::mbstowcs;
 using std::mbtowc;
 using std::qsort;
+#if defined(_GNU_SOURCE) || defined(__EXTENSIONS__)
+using std::qsort_r;
+#endif
 using std::rand;
 using std::realloc;
 using std::srand;