diff --git a/configure.in b/configure.in
index 7432fa97a6..1497813985 100644
--- a/configure.in
+++ b/configure.in
@@ -171,7 +171,7 @@ dnl -------------------------------------------------------------------
 dnl Check for functions before libevent, since libevent-1.2 apparently
 dnl exports strlcpy without defining it in a header.
 
-AC_CHECK_FUNCS(gettimeofday ftime socketpair uname inet_aton strptime getrlimit strlcat strlcpy strtoull ftello getaddrinfo localtime_r gmtime_r memmem strtok_r inet_pton inet_ntop mallinfo)
+AC_CHECK_FUNCS(gettimeofday ftime socketpair uname inet_aton strptime getrlimit strlcat strlcpy strtoull ftello getaddrinfo localtime_r gmtime_r memmem strtok_r inet_pton inet_ntop mallinfo malloc_good_size malloc_usable_size)
 
 if test "$enable_threads" = "yes"; then
   AC_CHECK_HEADERS(pthread.h)
@@ -266,7 +266,7 @@ AC_CHECK_HEADERS(netdb.h sys/ioctl.h sys/socket.h arpa/inet.h netinet/in.h pwd.h
 
 dnl These headers are not essential
 
-AC_CHECK_HEADERS(stdint.h sys/types.h inttypes.h sys/param.h sys/wait.h limits.h sys/limits.h netinet/in.h arpa/inet.h machine/limits.h syslog.h sys/time.h sys/resource.h inttypes.h utime.h sys/utime.h sys/mman.h netintet/in.h netinet/in6.h malloc.h sys/syslimits.h)
+AC_CHECK_HEADERS(stdint.h sys/types.h inttypes.h sys/param.h sys/wait.h limits.h sys/limits.h netinet/in.h arpa/inet.h machine/limits.h syslog.h sys/time.h sys/resource.h inttypes.h utime.h sys/utime.h sys/mman.h netintet/in.h netinet/in6.h malloc.h sys/syslimits.h malloc/malloc.h)
 
 AC_CHECK_HEADERS(net/if.h, net_if_found=1, net_if_found=0,
 [#ifdef HAVE_SYS_TYPES_H
diff --git a/src/common/mempool.c b/src/common/mempool.c
index 142ba0b9ae..36eb0e545f 100644
--- a/src/common/mempool.c
+++ b/src/common/mempool.c
@@ -78,6 +78,7 @@
 #define ASSERT(x) tor_assert(x)
 #undef ALLOC_CAN_RETURN_NULL
 #define TOR
+//#define ALLOC_ROUNDUP(p) tor_malloc_roundup(p)
 /* End Tor dependencies */
 #else
 /* If you're not building this as part of Tor, you'll want to define the
@@ -172,12 +173,22 @@ static mp_chunk_t *
 mp_chunk_new(mp_pool_t *pool)
 {
   size_t sz = pool->new_chunk_capacity * pool->item_alloc_size;
+#ifdef ALLOC_ROUNDUP
+  size_t alloc_size = CHUNK_OVERHEAD + sz;
+  mp_chunk_t *chunk = ALLOC_ROUNDUP(&alloc_size);
+#else
   mp_chunk_t *chunk = ALLOC(CHUNK_OVERHEAD + sz);
+#endif
   CHECK_ALLOC(chunk);
   memset(chunk, 0, sizeof(mp_chunk_t)); /* Doesn't clear the whole thing. */
   chunk->magic = MP_CHUNK_MAGIC;
+#ifdef ALLOC_ROUNDUP
+  chunk->mem_size = alloc_size - CHUNK_OVERHEAD;
+  chunk->capacity = chunk->mem_size / pool->item_alloc_size;
+#else
   chunk->capacity = pool->new_chunk_capacity;
   chunk->mem_size = sz;
+#endif
   chunk->next_mem = chunk->mem;
   chunk->pool = pool;
   return chunk;
diff --git a/src/common/util.c b/src/common/util.c
index 91f588ba47..d11b508b92 100644
--- a/src/common/util.c
+++ b/src/common/util.c
@@ -69,7 +69,10 @@ const char util_c_id[] = "$Id$";
 #ifdef HAVE_TIME_H
 #include <time.h>
 #endif
-#if defined(HAVE_MALLOC_H) && defined(HAVE_MALLINFO)
+#ifdef HAVE_MALLOC_MALLOC_H
+#include <malloc/malloc.h>
+#endif
+#ifdef HAVE_MALLOC_H
 #include <malloc.h>
 #endif
 
@@ -221,6 +224,26 @@ _tor_free(void *mem)
   tor_free(mem);
 }
 
+/** Allocate and return a chunk of memory of size at least *<b>size</p>, using
+ * the same resources we would use to malloc *<b>sizep</b>.  Set *<b>sizep</b>
+ * to the number of usable bytes in the chunk of memory. */
+void *
+_tor_malloc_roundup(size_t *sizep DMALLOC_PARAMS)
+{
+#ifdef HAVE_MALLOC_GOOD_SIZE
+  *sizep = malloc_good_size(*sizep);
+  return _tor_malloc(*sizep DMALLOC_FN_ARGS);
+#else
+#if defined(HAVE_MALLOC_USABLE_SIZE) && !defined(USE_DMALLOC)
+  void *result = _tor_malloc(*sizep DMALLOC_FN_ARGS);
+  *sizep = malloc_usable_size(result);
+  return result;
+#else
+  return _tor_malloc(*sizep);
+#endif
+#endif
+}
+
 /** Call the platform malloc info function, and dump the results to the log at
  * level <b>severity</b>.  If no such function exists, do nothing. */
 void
diff --git a/src/common/util.h b/src/common/util.h
index c0343cf2fd..d69c919964 100644
--- a/src/common/util.h
+++ b/src/common/util.h
@@ -75,6 +75,7 @@
 /* Memory management */
 void *_tor_malloc(size_t size DMALLOC_PARAMS) ATTR_MALLOC;
 void *_tor_malloc_zero(size_t size DMALLOC_PARAMS) ATTR_MALLOC;
+void *_tor_malloc_roundup(size_t *size DMALLOC_PARAMS) ATTR_MALLOC;
 void *_tor_realloc(void *ptr, size_t size DMALLOC_PARAMS);
 char *_tor_strdup(const char *s DMALLOC_PARAMS) ATTR_MALLOC ATTR_NONNULL((1));
 char *_tor_strndup(const char *s, size_t n DMALLOC_PARAMS)
@@ -102,6 +103,7 @@ extern int dmalloc_free(const char *file, const int line, void *pnt,
 
 #define tor_malloc(size)       _tor_malloc(size DMALLOC_ARGS)
 #define tor_malloc_zero(size)  _tor_malloc_zero(size DMALLOC_ARGS)
+#define tor_malloc_roundup(szp) _tor_malloc_roundup(szp DMALLOC_ARGS)
 #define tor_realloc(ptr, size) _tor_realloc(ptr, size DMALLOC_ARGS)
 #define tor_strdup(s)          _tor_strdup(s DMALLOC_ARGS)
 #define tor_strndup(s, n)      _tor_strndup(s, n DMALLOC_ARGS)