diff --git a/jemalloc/src/internal/jemalloc_chunk.h b/jemalloc/src/internal/jemalloc_chunk.h
index 74401684..13b72ed4 100644
--- a/jemalloc/src/internal/jemalloc_chunk.h
+++ b/jemalloc/src/internal/jemalloc_chunk.h
@@ -43,7 +43,7 @@ extern size_t		chunk_npages;
 extern size_t		arena_chunk_header_npages;
 extern size_t		arena_maxclass; /* Max size class for arenas. */
 
-void	*chunk_alloc(size_t size, bool zero);
+void	*chunk_alloc(size_t size, bool *zero);
 void	chunk_dealloc(void *chunk, size_t size);
 bool	chunk_boot(void);
 
diff --git a/jemalloc/src/internal/jemalloc_chunk_dss.h b/jemalloc/src/internal/jemalloc_chunk_dss.h
index dc7b38ea..6be4ad1f 100644
--- a/jemalloc/src/internal/jemalloc_chunk_dss.h
+++ b/jemalloc/src/internal/jemalloc_chunk_dss.h
@@ -16,7 +16,7 @@
  */
 extern malloc_mutex_t	dss_mtx;
 
-void	*chunk_alloc_dss(size_t size, bool zero);
+void	*chunk_alloc_dss(size_t size, bool *zero);
 bool	chunk_dealloc_dss(void *chunk, size_t size);
 bool	chunk_dss_boot(void);
 
diff --git a/jemalloc/src/internal/jemalloc_chunk_swap.h b/jemalloc/src/internal/jemalloc_chunk_swap.h
index 3d5c5d21..5bdf3073 100644
--- a/jemalloc/src/internal/jemalloc_chunk_swap.h
+++ b/jemalloc/src/internal/jemalloc_chunk_swap.h
@@ -16,7 +16,7 @@ extern bool		swap_enabled;
 extern size_t		swap_avail;
 #endif
 
-void	*chunk_alloc_swap(size_t size, bool zero);
+void	*chunk_alloc_swap(size_t size, bool *zero);
 bool	chunk_dealloc_swap(void *chunk, size_t size);
 bool	chunk_swap_enable(const int *fds, unsigned nfds, bool prezeroed);
 bool	chunk_swap_boot(void);
diff --git a/jemalloc/src/jemalloc_arena.c b/jemalloc/src/jemalloc_arena.c
index 3dbf47df..e8b21d75 100644
--- a/jemalloc/src/jemalloc_arena.c
+++ b/jemalloc/src/jemalloc_arena.c
@@ -586,7 +586,11 @@ arena_chunk_alloc(arena_t *arena)
 		chunk = arena->spare;
 		arena->spare = NULL;
 	} else {
-		chunk = (arena_chunk_t *)chunk_alloc(chunksize, true);
+		bool zero;
+		size_t zeroed;
+
+		zero = false;
+		chunk = (arena_chunk_t *)chunk_alloc(chunksize, &zero);
 		if (chunk == NULL)
 			return (NULL);
 #ifdef JEMALLOC_STATS
@@ -604,15 +608,16 @@ arena_chunk_alloc(arena_t *arena)
 
 		/*
 		 * Initialize the map to contain one maximal free untouched run.
+		 * Mark the pages as zeroed iff chunk_alloc() returned a zeroed
+		 * chunk.
 		 */
+		zeroed = zero ? CHUNK_MAP_ZEROED : 0;
 		for (i = 0; i < arena_chunk_header_npages; i++)
 			chunk->map[i].bits = 0;
-		chunk->map[i].bits = arena_maxclass | CHUNK_MAP_ZEROED;
-		for (i++; i < chunk_npages-1; i++) {
-			chunk->map[i].bits = CHUNK_MAP_ZEROED;
-		}
-		chunk->map[chunk_npages-1].bits = arena_maxclass |
-		    CHUNK_MAP_ZEROED;
+		chunk->map[i].bits = arena_maxclass | zeroed;
+		for (i++; i < chunk_npages-1; i++)
+			chunk->map[i].bits = zeroed;
+		chunk->map[chunk_npages-1].bits = arena_maxclass | zeroed;
 	}
 
 	/* Insert the run into the runs_avail tree. */
diff --git a/jemalloc/src/jemalloc_base.c b/jemalloc/src/jemalloc_base.c
index bb88f7cf..607f94a4 100644
--- a/jemalloc/src/jemalloc_base.c
+++ b/jemalloc/src/jemalloc_base.c
@@ -27,10 +27,12 @@ static bool
 base_pages_alloc(size_t minsize)
 {
 	size_t csize;
+	bool zero;
 
 	assert(minsize != 0);
 	csize = CHUNK_CEILING(minsize);
-	base_pages = chunk_alloc(csize, false);
+	zero = false;
+	base_pages = chunk_alloc(csize, &zero);
 	if (base_pages == NULL)
 		return (true);
 	base_next_addr = base_pages;
diff --git a/jemalloc/src/jemalloc_chunk.c b/jemalloc/src/jemalloc_chunk.c
index 2da85a6c..c42151dc 100644
--- a/jemalloc/src/jemalloc_chunk.c
+++ b/jemalloc/src/jemalloc_chunk.c
@@ -22,8 +22,14 @@ size_t		arena_maxclass; /* Max size class for arenas. */
 
 /******************************************************************************/
 
+/*
+ * If the caller specifies (*zero == false), it is still possible to receive
+ * zeroed memory, in which case *zero is toggled to true.  arena_chunk_alloc()
+ * takes advantage of this to avoid demanding zeroed chunks, but taking
+ * advantage of them if they are returned.
+ */
 void *
-chunk_alloc(size_t size, bool zero)
+chunk_alloc(size_t size, bool *zero)
 {
 	void *ret;
 
@@ -45,8 +51,10 @@ chunk_alloc(size_t size, bool zero)
 			goto RETURN;
 #endif
 		ret = chunk_alloc_mmap(size);
-		if (ret != NULL)
+		if (ret != NULL) {
+			*zero = true;
 			goto RETURN;
+		}
 #ifdef JEMALLOC_SWAP
 	}
 #endif
diff --git a/jemalloc/src/jemalloc_chunk_dss.c b/jemalloc/src/jemalloc_chunk_dss.c
index 4a4bb5f8..7c6cdd61 100644
--- a/jemalloc/src/jemalloc_chunk_dss.c
+++ b/jemalloc/src/jemalloc_chunk_dss.c
@@ -25,13 +25,13 @@ static extent_tree_t	dss_chunks_ad;
 /******************************************************************************/
 /* Function prototypes for non-inline static functions. */
 
-static void	*chunk_recycle_dss(size_t size, bool zero);
+static void	*chunk_recycle_dss(size_t size, bool *zero);
 static extent_node_t *chunk_dealloc_dss_record(void *chunk, size_t size);
 
 /******************************************************************************/
 
 static void *
-chunk_recycle_dss(size_t size, bool zero)
+chunk_recycle_dss(size_t size, bool *zero)
 {
 	extent_node_t *node, key;
 
@@ -60,7 +60,7 @@ chunk_recycle_dss(size_t size, bool zero)
 		}
 		malloc_mutex_unlock(&dss_mtx);
 
-		if (zero)
+		if (*zero)
 			memset(ret, 0, size);
 		return (ret);
 	}
@@ -70,7 +70,7 @@ chunk_recycle_dss(size_t size, bool zero)
 }
 
 void *
-chunk_alloc_dss(size_t size, bool zero)
+chunk_alloc_dss(size_t size, bool *zero)
 {
 	void *ret;
 
@@ -116,6 +116,7 @@ chunk_alloc_dss(size_t size, bool zero)
 				/* Success. */
 				dss_max = (void *)((intptr_t)dss_prev + incr);
 				malloc_mutex_unlock(&dss_mtx);
+				*zero = true;
 				return (ret);
 			}
 		} while (dss_prev != (void *)-1);
diff --git a/jemalloc/src/jemalloc_chunk_swap.c b/jemalloc/src/jemalloc_chunk_swap.c
index a0cb40b0..0a304714 100644
--- a/jemalloc/src/jemalloc_chunk_swap.c
+++ b/jemalloc/src/jemalloc_chunk_swap.c
@@ -31,13 +31,13 @@ static extent_tree_t	swap_chunks_ad;
 /******************************************************************************/
 /* Function prototypes for non-inline static functions. */
 
-static void	*chunk_recycle_swap(size_t size, bool zero);
+static void	*chunk_recycle_swap(size_t size, bool *zero);
 static extent_node_t *chunk_dealloc_swap_record(void *chunk, size_t size);
 
 /******************************************************************************/
 
 static void *
-chunk_recycle_swap(size_t size, bool zero)
+chunk_recycle_swap(size_t size, bool *zero)
 {
 	extent_node_t *node, key;
 
@@ -69,7 +69,7 @@ chunk_recycle_swap(size_t size, bool zero)
 #endif
 		malloc_mutex_unlock(&swap_mtx);
 
-		if (zero)
+		if (*zero)
 			memset(ret, 0, size);
 		return (ret);
 	}
@@ -79,7 +79,7 @@ chunk_recycle_swap(size_t size, bool zero)
 }
 
 void *
-chunk_alloc_swap(size_t size, bool zero)
+chunk_alloc_swap(size_t size, bool *zero)
 {
 	void *ret;
 
@@ -98,7 +98,9 @@ chunk_alloc_swap(size_t size, bool zero)
 #endif
 		malloc_mutex_unlock(&swap_mtx);
 
-		if (zero && swap_prezeroed == false)
+		if (swap_prezeroed)
+			*zero = true;
+		else if (*zero)
 			memset(ret, 0, size);
 	} else {
 		malloc_mutex_unlock(&swap_mtx);
diff --git a/jemalloc/src/jemalloc_huge.c b/jemalloc/src/jemalloc_huge.c
index 78551795..b914b45c 100644
--- a/jemalloc/src/jemalloc_huge.c
+++ b/jemalloc/src/jemalloc_huge.c
@@ -37,7 +37,7 @@ huge_malloc(size_t size, bool zero)
 	if (node == NULL)
 		return (NULL);
 
-	ret = chunk_alloc(csize, zero);
+	ret = chunk_alloc(csize, &zero);
 	if (ret == NULL) {
 		base_node_dealloc(node);
 		return (NULL);
@@ -74,6 +74,7 @@ huge_palloc(size_t alignment, size_t size)
 	void *ret;
 	size_t alloc_size, chunk_size, offset;
 	extent_node_t *node;
+	bool zero;
 
 	/*
 	 * This allocation requires alignment that is even larger than chunk
@@ -97,7 +98,8 @@ huge_palloc(size_t alignment, size_t size)
 	if (node == NULL)
 		return (NULL);
 
-	ret = chunk_alloc(alloc_size, false);
+	zero = false;
+	ret = chunk_alloc(alloc_size, &zero);
 	if (ret == NULL) {
 		base_node_dealloc(node);
 		return (NULL);