diff --git a/include/jemalloc/internal/bitmap.h b/include/jemalloc/internal/bitmap.h
index a53ac799..ee2e7e9d 100644
--- a/include/jemalloc/internal/bitmap.h
+++ b/include/jemalloc/internal/bitmap.h
@@ -15,6 +15,15 @@ typedef unsigned long bitmap_t;
 #define	BITMAP_GROUP_NBITS		(ZU(1) << LG_BITMAP_GROUP_NBITS)
 #define	BITMAP_GROUP_NBITS_MASK		(BITMAP_GROUP_NBITS-1)
 
+/*
+ * Do some analysis on how big the bitmap is before we use a tree.  For a brute
+ * force linear search, if we would have to call ffsl more than 2^3 times, use a
+ * tree instead.
+ */
+#if LG_RUN_MAXREGS - LG_BITMAP_GROUP_NBITS > 3
+#  define USE_TREE
+#endif
+
 /* Number of groups required to store a given number of bits. */
 #define	BITMAP_BITS2GROUPS(nbits)					\
     ((nbits + BITMAP_GROUP_NBITS_MASK) >> LG_BITMAP_GROUP_NBITS)
@@ -48,6 +57,8 @@ typedef unsigned long bitmap_t;
 /*
  * Maximum number of groups required to support LG_BITMAP_MAXBITS.
  */
+#ifdef USE_TREE
+
 #if LG_BITMAP_MAXBITS <= LG_BITMAP_GROUP_NBITS
 #  define BITMAP_GROUPS_MAX	BITMAP_GROUPS_1_LEVEL(BITMAP_MAXBITS)
 #elif LG_BITMAP_MAXBITS <= LG_BITMAP_GROUP_NBITS * 2
@@ -65,6 +76,13 @@ typedef unsigned long bitmap_t;
     (LG_BITMAP_MAXBITS / LG_SIZEOF_BITMAP)				\
     + !!(LG_BITMAP_MAXBITS % LG_SIZEOF_BITMAP)
 
+#else /* USE_TREE */
+
+#define	BITMAP_GROUPS_MAX						\
+    (ZU(1) << (LG_RUN_MAXREGS - LG_SIZEOF_BITMAP - LG_SIZEOF_BITMAP))
+
+#endif /* USE_TREE */
+
 #endif /* JEMALLOC_H_TYPES */
 /******************************************************************************/
 #ifdef JEMALLOC_H_STRUCTS
@@ -78,6 +96,7 @@ struct bitmap_info_s {
 	/* Logical number of bits in bitmap (stored at bottom level). */
 	size_t nbits;
 
+#ifdef USE_TREE
 	/* Number of levels necessary for nbits. */
 	unsigned nlevels;
 
@@ -86,6 +105,10 @@ struct bitmap_info_s {
 	 * bottom to top (e.g. the bottom level is stored in levels[0]).
 	 */
 	bitmap_level_t levels[BITMAP_MAX_LEVELS+1];
+#else /* USE_TREE */
+	/* Number of groups necessary for nbits. */
+	size_t ngroups;
+#endif /* USE_TREE */
 };
 
 #endif /* JEMALLOC_H_STRUCTS */
@@ -112,10 +135,20 @@ void	bitmap_unset(bitmap_t *bitmap, const bitmap_info_t *binfo, size_t bit);
 JEMALLOC_INLINE bool
 bitmap_full(bitmap_t *bitmap, const bitmap_info_t *binfo)
 {
+#ifdef USE_TREE
 	size_t rgoff = binfo->levels[binfo->nlevels].group_offset - 1;
 	bitmap_t rg = bitmap[rgoff];
 	/* The bitmap is full iff the root group is 0. */
 	return (rg == 0);
+#else
+	size_t i;
+
+	for (i = 0; i < binfo->ngroups; i++) {
+		if (bitmap[i] != 0)
+			return (false);
+	}
+	return (true);
+#endif
 }
 
 JEMALLOC_INLINE bool
@@ -146,6 +179,7 @@ bitmap_set(bitmap_t *bitmap, const bitmap_info_t *binfo, size_t bit)
 	g ^= ZU(1) << (bit & BITMAP_GROUP_NBITS_MASK);
 	*gp = g;
 	assert(bitmap_get(bitmap, binfo, bit));
+#ifdef USE_TREE
 	/* Propagate group state transitions up the tree. */
 	if (g == 0) {
 		unsigned i;
@@ -161,6 +195,7 @@ bitmap_set(bitmap_t *bitmap, const bitmap_info_t *binfo, size_t bit)
 				break;
 		}
 	}
+#endif
 }
 
 /* sfu: set first unset. */
@@ -173,6 +208,7 @@ bitmap_sfu(bitmap_t *bitmap, const bitmap_info_t *binfo)
 
 	assert(!bitmap_full(bitmap, binfo));
 
+#ifdef USE_TREE
 	i = binfo->nlevels - 1;
 	g = bitmap[binfo->levels[i].group_offset];
 	bit = ffs_lu(g) - 1;
@@ -181,7 +217,15 @@ bitmap_sfu(bitmap_t *bitmap, const bitmap_info_t *binfo)
 		g = bitmap[binfo->levels[i].group_offset + bit];
 		bit = (bit << LG_BITMAP_GROUP_NBITS) + (ffs_lu(g) - 1);
 	}
-
+#else
+	i = 0;
+	g = bitmap[0];
+	while ((bit = ffs_lu(g)) == 0) {
+		i++;
+		g = bitmap[i];
+	}
+	bit = (bit - 1) + (i << 6);
+#endif
 	bitmap_set(bitmap, binfo, bit);
 	return (bit);
 }
@@ -192,7 +236,7 @@ bitmap_unset(bitmap_t *bitmap, const bitmap_info_t *binfo, size_t bit)
 	size_t goff;
 	bitmap_t *gp;
 	bitmap_t g;
-	bool propagate;
+	UNUSED bool propagate;
 
 	assert(bit < binfo->nbits);
 	assert(bitmap_get(bitmap, binfo, bit));
@@ -204,6 +248,7 @@ bitmap_unset(bitmap_t *bitmap, const bitmap_info_t *binfo, size_t bit)
 	g ^= ZU(1) << (bit & BITMAP_GROUP_NBITS_MASK);
 	*gp = g;
 	assert(!bitmap_get(bitmap, binfo, bit));
+#ifdef USE_TREE
 	/* Propagate group state transitions up the tree. */
 	if (propagate) {
 		unsigned i;
@@ -221,6 +266,7 @@ bitmap_unset(bitmap_t *bitmap, const bitmap_info_t *binfo, size_t bit)
 				break;
 		}
 	}
+#endif /* USE_TREE */
 }
 
 #endif
diff --git a/src/bitmap.c b/src/bitmap.c
index 22c92fe4..b1e66271 100644
--- a/src/bitmap.c
+++ b/src/bitmap.c
@@ -3,6 +3,8 @@
 
 /******************************************************************************/
 
+#ifdef USE_TREE
+
 void
 bitmap_info_init(bitmap_info_t *binfo, size_t nbits)
 {
@@ -32,6 +34,13 @@ bitmap_info_init(bitmap_info_t *binfo, size_t nbits)
 	binfo->nbits = nbits;
 }
 
+static size_t
+bitmap_info_ngroups(const bitmap_info_t *binfo)
+{
+
+	return (binfo->levels[binfo->nlevels].group_offset);
+}
+
 void
 bitmap_init(bitmap_t *bitmap, const bitmap_info_t *binfo)
 {
@@ -60,13 +69,43 @@ bitmap_init(bitmap_t *bitmap, const bitmap_info_t *binfo)
 	}
 }
 
+#else /* USE_TREE */
+
+void
+bitmap_info_init(bitmap_info_t *binfo, size_t nbits)
+{
+	size_t i;
+
+	assert(nbits > 0);
+	assert(nbits <= (ZU(1) << LG_BITMAP_MAXBITS));
+
+	i = nbits >> LG_BITMAP_GROUP_NBITS;
+	if (nbits % BITMAP_GROUP_NBITS != 0)
+		i++;
+	binfo->ngroups = i;
+	binfo->nbits = nbits;
+}
+
 static size_t
 bitmap_info_ngroups(const bitmap_info_t *binfo)
 {
 
-	return (binfo->levels[binfo->nlevels].group_offset);
+	return (binfo->ngroups);
 }
 
+void
+bitmap_init(bitmap_t *bitmap, const bitmap_info_t *binfo)
+{
+	size_t extra;
+
+	memset(bitmap, 0xffU, bitmap_size(binfo));
+	extra = (binfo->nbits % (binfo->ngroups * BITMAP_GROUP_NBITS));
+	if (extra != 0)
+		bitmap[binfo->ngroups - 1] >>= (BITMAP_GROUP_NBITS - extra);
+}
+
+#endif /* USE_TREE */
+
 size_t
 bitmap_size(const bitmap_info_t *binfo)
 {