diff --git a/libc/Android.mk b/libc/Android.mk
index 5718d18..c76f0c9 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -154,6 +154,7 @@
 	stdlib/nrand48.c \
 	stdlib/putenv.c \
 	stdlib/qsort.c \
+	stdlib/qsort_r.c \
 	stdlib/seed48.c \
 	stdlib/setenv.c \
 	stdlib/setjmperr.c \
diff --git a/libc/include/stdlib.h b/libc/include/stdlib.h
index acfe694..4f18833 100644
--- a/libc/include/stdlib.h
+++ b/libc/include/stdlib.h
@@ -101,6 +101,7 @@
 	int (*compar)(const void *, const void *));
 
 extern void qsort(void *, size_t, size_t, int (*)(const void *, const void *));
+extern void qsort_r(void *a, size_t n, size_t es, void *thunk, int (*)(void *, const void *, const void *));
 
 extern long jrand48(unsigned short *);
 extern long mrand48(void);
diff --git a/libc/stdlib/qsort.c b/libc/stdlib/qsort.c
index cd66961..3748483 100644
--- a/libc/stdlib/qsort.c
+++ b/libc/stdlib/qsort.c
@@ -1,4 +1,3 @@
-/*	$OpenBSD: qsort.c,v 1.10 2005/08/08 08:05:37 espie Exp $ */
 /*-
  * Copyright (c) 1992, 1993
  *	The Regents of the University of California.  All rights reserved.
@@ -11,7 +10,7 @@
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
+ * 4. Neither the name of the University nor the names of its contributors
  *    may be used to endorse or promote products derived from this software
  *    without specific prior written permission.
  *
@@ -28,11 +27,16 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/types.h>
+#include <sys/cdefs.h>
 #include <stdlib.h>
 
-static __inline char	*med3(char *, char *, char *, int (*)(const void *, const void *));
-static __inline void	 swapfunc(char *, char *, int, int);
+#ifdef I_AM_QSORT_R
+typedef int		 cmp_t(void *, const void *, const void *);
+#else
+typedef int		 cmp_t(const void *, const void *);
+#endif
+static inline char	*med3(char *, char *, char *, cmp_t *, void *);
+static inline void	 swapfunc(char *, char *, int, int);
 
 #define min(a, b)	(a) < (b) ? a : b
 
@@ -41,10 +45,10 @@
  */
 #define swapcode(TYPE, parmi, parmj, n) { 		\
 	long i = (n) / sizeof (TYPE); 			\
-	TYPE *pi = (TYPE *) (parmi); 			\
-	TYPE *pj = (TYPE *) (parmj); 			\
+	TYPE *pi = (TYPE *) (parmi); 		\
+	TYPE *pj = (TYPE *) (parmj); 		\
 	do { 						\
-		TYPE	t = *pi;			\
+		TYPE	t = *pi;		\
 		*pi++ = *pj;				\
 		*pj++ = t;				\
         } while (--i > 0);				\
@@ -53,10 +57,12 @@
 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
 	es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
 
-static __inline void
-swapfunc(char *a, char *b, int n, int swaptype)
+static inline void
+swapfunc(a, b, n, swaptype)
+	char *a, *b;
+	int n, swaptype;
 {
-	if (swaptype <= 1) 
+	if(swaptype <= 1)
 		swapcode(long, a, b, n)
 	else
 		swapcode(char, a, b, n)
@@ -72,57 +78,75 @@
 
 #define vecswap(a, b, n) 	if ((n) > 0) swapfunc(a, b, n, swaptype)
 
-static __inline char *
-med3(char *a, char *b, char *c, int (*cmp)(const void *, const void *))
+#ifdef I_AM_QSORT_R
+#define	CMP(t, x, y) (cmp((t), (x), (y)))
+#else
+#define	CMP(t, x, y) (cmp((x), (y)))
+#endif
+
+static inline char *
+med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk
+#ifndef I_AM_QSORT_R
+__unused
+#endif
+)
 {
-	return cmp(a, b) < 0 ?
-	       (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
-              :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
+	return CMP(thunk, a, b) < 0 ?
+	       (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a ))
+              :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c ));
 }
 
+#ifdef I_AM_QSORT_R
 void
-qsort(void *aa, size_t n, size_t es, int (*cmp)(const void *, const void *))
+qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
+#else
+#define thunk NULL
+void
+qsort(void *a, size_t n, size_t es, cmp_t *cmp)
+#endif
 {
 	char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
-	int d, r, swaptype, swap_cnt;
-	char *a = aa;
+	size_t d, r;
+	int cmp_result;
+	int swaptype, swap_cnt;
 
 loop:	SWAPINIT(a, es);
 	swap_cnt = 0;
 	if (n < 7) {
-		for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es)
-			for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
+		for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
+			for (pl = pm; 
+			     pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
 			     pl -= es)
 				swap(pl, pl - es);
 		return;
 	}
 	pm = (char *)a + (n / 2) * es;
 	if (n > 7) {
-		pl = (char *)a;
+		pl = a;
 		pn = (char *)a + (n - 1) * es;
 		if (n > 40) {
 			d = (n / 8) * es;
-			pl = med3(pl, pl + d, pl + 2 * d, cmp);
-			pm = med3(pm - d, pm, pm + d, cmp);
-			pn = med3(pn - 2 * d, pn - d, pn, cmp);
+			pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
+			pm = med3(pm - d, pm, pm + d, cmp, thunk);
+			pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
 		}
-		pm = med3(pl, pm, pn, cmp);
+		pm = med3(pl, pm, pn, cmp, thunk);
 	}
 	swap(a, pm);
 	pa = pb = (char *)a + es;
-    
+
 	pc = pd = (char *)a + (n - 1) * es;
 	for (;;) {
-		while (pb <= pc && (r = cmp(pb, a)) <= 0) {
-			if (r == 0) {
+		while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) {
+			if (cmp_result == 0) {
 				swap_cnt = 1;
 				swap(pa, pb);
 				pa += es;
-      }
+			}
 			pb += es;
 		}
-		while (pb <= pc && (r = cmp(pc, a)) >= 0) {
-			if (r == 0) {
+		while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) {
+			if (cmp_result == 0) {
 				swap_cnt = 1;
 				swap(pc, pd);
 				pd -= es;
@@ -137,21 +161,26 @@
 		pc -= es;
 	}
 	if (swap_cnt == 0) {  /* Switch to insertion sort */
-		for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
-			for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 
+		for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
+			for (pl = pm; 
+			     pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
 			     pl -= es)
 				swap(pl, pl - es);
 		return;
-    }
+	}
 
 	pn = (char *)a + n * es;
 	r = min(pa - (char *)a, pb - pa);
 	vecswap(a, pb - r, r);
 	r = min(pd - pc, pn - pd - (int)es);
 	vecswap(pb, pn - r, r);
-	if ((r = pb - pa) > (int)es)
+	if ((r = pb - pa) > es)
+#ifdef I_AM_QSORT_R
+		qsort_r(a, r / es, es, thunk, cmp);
+#else
 		qsort(a, r / es, es, cmp);
-	if ((r = pd - pc) > (int)es) { 
+#endif
+	if ((r = pd - pc) > es) {
 		/* Iterate rather than recurse to save stack space */
 		a = pn - r;
 		n = r / es;
diff --git a/libc/stdlib/qsort_r.c b/libc/stdlib/qsort_r.c
new file mode 100644
index 0000000..d57f3d3
--- /dev/null
+++ b/libc/stdlib/qsort_r.c
@@ -0,0 +1,8 @@
+/*
+ * This file is in the public domain.  Originally written by Garrett
+ * A. Wollman.
+ *
+ * $FreeBSD: src/lib/libc/stdlib/qsort_r.c,v 1.1.36.1.2.1 2009/10/25 01:10:29 kensmith Exp $
+ */
+#define I_AM_QSORT_R
+#include "qsort.c"