diff --git a/include/jemalloc/internal/arena.h b/include/jemalloc/internal/arena.h
index 3519873c..babd5129 100644
--- a/include/jemalloc/internal/arena.h
+++ b/include/jemalloc/internal/arena.h
@@ -36,6 +36,7 @@ typedef enum {
 #define	DECAY_NTICKS_PER_UPDATE	1000
 
 typedef struct arena_runs_dirty_link_s arena_runs_dirty_link_t;
+typedef struct arena_avail_links_s arena_avail_links_t;
 typedef struct arena_run_s arena_run_t;
 typedef struct arena_chunk_map_bits_s arena_chunk_map_bits_t;
 typedef struct arena_chunk_map_misc_s arena_chunk_map_misc_t;
@@ -146,6 +147,11 @@ struct arena_runs_dirty_link_s {
 	qr(arena_runs_dirty_link_t)	rd_link;
 };
 
+struct arena_avail_links_s {
+	arena_runs_dirty_link_t		rd;
+	ph_node_t			ph_link;
+};
+
 /*
  * Each arena_chunk_map_misc_t corresponds to one page within the chunk, just
  * like arena_chunk_map_bits_t.  Two separate arrays are stored within each
@@ -163,7 +169,7 @@ struct arena_chunk_map_misc_s {
 
 	union {
 		/* Linkage for list of dirty runs. */
-		arena_runs_dirty_link_t		rd;
+		arena_avail_links_t		avail;
 
 		/* Profile counters, used for large object runs. */
 		union {
@@ -457,10 +463,10 @@ struct arena_s {
 	arena_bin_t		bins[NBINS];
 
 	/*
-	 * Quantized address-ordered trees of this arena's available runs.  The
-	 * trees are used for first-best-fit run allocation.
+	 * Quantized address-ordered heaps of this arena's available runs.  The
+	 * heaps are used for first-best-fit run allocation.
 	 */
-	arena_run_tree_t	runs_avail[1]; /* Dynamically sized. */
+	ph_heap_t		runs_avail[1]; /* Dynamically sized. */
 };
 
 /* Used in conjunction with tsd for fast arena-related context lookup. */
@@ -600,6 +606,7 @@ arena_chunk_map_misc_t	*arena_miscelm_get(arena_chunk_t *chunk,
 size_t	arena_miscelm_to_pageind(const arena_chunk_map_misc_t *miscelm);
 void	*arena_miscelm_to_rpages(arena_chunk_map_misc_t *miscelm);
 arena_chunk_map_misc_t	*arena_rd_to_miscelm(arena_runs_dirty_link_t *rd);
+arena_chunk_map_misc_t	*arena_ph_to_miscelm(ph_node_t *ph);
 arena_chunk_map_misc_t	*arena_run_to_miscelm(arena_run_t *run);
 size_t	*arena_mapbitsp_get(arena_chunk_t *chunk, size_t pageind);
 size_t	arena_mapbitsp_read(size_t *mapbitsp);
@@ -702,7 +709,19 @@ JEMALLOC_ALWAYS_INLINE arena_chunk_map_misc_t *
 arena_rd_to_miscelm(arena_runs_dirty_link_t *rd)
 {
 	arena_chunk_map_misc_t *miscelm = (arena_chunk_map_misc_t
-	    *)((uintptr_t)rd - offsetof(arena_chunk_map_misc_t, rd));
+	    *)((uintptr_t)rd - offsetof(arena_chunk_map_misc_t, avail));
+
+	assert(arena_miscelm_to_pageind(miscelm) >= map_bias);
+	assert(arena_miscelm_to_pageind(miscelm) < chunk_npages);
+
+	return (miscelm);
+}
+
+JEMALLOC_ALWAYS_INLINE arena_chunk_map_misc_t *
+arena_ph_to_miscelm(ph_node_t *ph)
+{
+	arena_chunk_map_misc_t *miscelm = (arena_chunk_map_misc_t *)
+	    ((uintptr_t)ph - offsetof(arena_chunk_map_misc_t, avail.ph_link));
 
 	assert(arena_miscelm_to_pageind(miscelm) >= map_bias);
 	assert(arena_miscelm_to_pageind(miscelm) < chunk_npages);
diff --git a/include/jemalloc/internal/private_symbols.txt b/include/jemalloc/internal/private_symbols.txt
index aeb43b1d..aed60cb1 100644
--- a/include/jemalloc/internal/private_symbols.txt
+++ b/include/jemalloc/internal/private_symbols.txt
@@ -79,6 +79,7 @@ arena_nthreads_dec
 arena_nthreads_get
 arena_nthreads_inc
 arena_palloc
+arena_ph_to_miscelm
 arena_postfork_child
 arena_postfork_parent
 arena_prefork
diff --git a/src/arena.c b/src/arena.c
index f436959e..fc9852df 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -199,7 +199,7 @@ run_quantize_ceil(size_t size)
 run_quantize_t *run_quantize_ceil = JEMALLOC_N(run_quantize_ceil_impl);
 #endif
 
-static arena_run_tree_t *
+static ph_heap_t *
 arena_runs_avail_get(arena_t *arena, szind_t ind)
 {
 
@@ -217,8 +217,8 @@ arena_avail_insert(arena_t *arena, arena_chunk_t *chunk, size_t pageind,
 	    arena_miscelm_get(chunk, pageind))));
 	assert(npages == (arena_mapbits_unallocated_size_get(chunk, pageind) >>
 	    LG_PAGE));
-	arena_run_tree_insert(arena_runs_avail_get(arena, ind),
-	    arena_miscelm_get(chunk, pageind));
+	ph_insert(arena_runs_avail_get(arena, ind),
+	    &arena_miscelm_get(chunk, pageind)->avail.ph_link);
 }
 
 static void
@@ -229,8 +229,8 @@ arena_avail_remove(arena_t *arena, arena_chunk_t *chunk, size_t pageind,
 	    arena_miscelm_get(chunk, pageind))));
 	assert(npages == (arena_mapbits_unallocated_size_get(chunk, pageind) >>
 	    LG_PAGE));
-	arena_run_tree_remove(arena_runs_avail_get(arena, ind),
-	    arena_miscelm_get(chunk, pageind));
+	ph_remove(arena_runs_avail_get(arena, ind),
+	    &arena_miscelm_get(chunk, pageind)->avail.ph_link);
 }
 
 static void
@@ -245,8 +245,8 @@ arena_run_dirty_insert(arena_t *arena, arena_chunk_t *chunk, size_t pageind,
 	assert(arena_mapbits_dirty_get(chunk, pageind+npages-1) ==
 	    CHUNK_MAP_DIRTY);
 
-	qr_new(&miscelm->rd, rd_link);
-	qr_meld(&arena->runs_dirty, &miscelm->rd, rd_link);
+	qr_new(&miscelm->avail.rd, rd_link);
+	qr_meld(&arena->runs_dirty, &miscelm->avail.rd, rd_link);
 	arena->ndirty += npages;
 }
 
@@ -262,7 +262,7 @@ arena_run_dirty_remove(arena_t *arena, arena_chunk_t *chunk, size_t pageind,
 	assert(arena_mapbits_dirty_get(chunk, pageind+npages-1) ==
 	    CHUNK_MAP_DIRTY);
 
-	qr_remove(&miscelm->rd, rd_link);
+	qr_remove(&miscelm->avail.rd, rd_link);
 	assert(arena->ndirty >= npages);
 	arena->ndirty -= npages;
 }
@@ -1079,10 +1079,12 @@ arena_run_first_best_fit(arena_t *arena, size_t size)
 
 	ind = size2index(run_quantize_ceil(size));
 	for (i = ind; i < runs_avail_nclasses + runs_avail_bias; i++) {
-		arena_chunk_map_misc_t *miscelm = arena_run_tree_first(
-		    arena_runs_avail_get(arena, i));
-		if (miscelm != NULL)
+		ph_node_t *node = ph_first(arena_runs_avail_get(arena, i));
+		if (node != NULL) {
+			arena_chunk_map_misc_t *miscelm =
+			    arena_ph_to_miscelm(node);
 			return (&miscelm->run);
+		}
 	}
 
 	return (NULL);
@@ -3323,7 +3325,7 @@ arena_new(unsigned ind)
 	arena_bin_t *bin;
 
 	/* Compute arena size to incorporate sufficient runs_avail elements. */
-	arena_size = offsetof(arena_t, runs_avail) + (sizeof(arena_run_tree_t) *
+	arena_size = offsetof(arena_t, runs_avail) + (sizeof(ph_heap_t) *
 	    runs_avail_nclasses);
 	/*
 	 * Allocate arena, arena->lstats, and arena->hstats contiguously, mainly
@@ -3383,7 +3385,7 @@ arena_new(unsigned ind)
 	arena->ndirty = 0;
 
 	for(i = 0; i < runs_avail_nclasses; i++)
-		arena_run_tree_new(&arena->runs_avail[i]);
+		ph_new(&arena->runs_avail[i]);
 	qr_new(&arena->runs_dirty, rd_link);
 	qr_new(&arena->chunks_cache, cc_link);