diff --git a/Android.mk b/Android.mk
index f9497cb..5acd474 100644
--- a/Android.mk
+++ b/Android.mk
@@ -22,6 +22,30 @@
 	-fvisibility=hidden \
 	-Wno-unused-parameter \
 
+# These parameters change the way jemalloc works.
+#   ANDROID_ALWAYS_PURGE
+#     If defined, always purge immediately when a page is purgeable.
+#   ANDROID_MAX_ARENAS=XX
+#     The total number of arenas will be less than or equal to this number.
+#     The number of arenas will be calculated as 2 * the number of cpus
+#     but no larger than XX.
+#   ANDROID_TCACHE_NSLOTS_SMALL_MAX=XX
+#     The number of small slots held in the tcache. The higher this number
+#     is, the higher amount of PSS consumed. If this number is set too low
+#     then small allocations will take longer to complete.
+#   ANDROID_TCACHE_NSLOTS_LARGE=XX
+#     The number of large slots held in the tcache. The higher this number
+#     is, the higher amount of PSS consumed. If this number is set too low
+#     then large allocations will take longer to complete.
+#   ANDROID_LG_TCACHE_MAXCLASS_DEFAULT=XX
+#     1 << XX is the maximum sized allocation that will be in the tcache.
+common_cflags += \
+	-DANDROID_ALWAYS_PURGE \
+	-DANDROID_MAX_ARENAS=2 \
+	-DANDROID_TCACHE_NSLOTS_SMALL_MAX=8 \
+	-DANDROID_TCACHE_NSLOTS_LARGE=16 \
+	-DANDROID_LG_TCACHE_MAXCLASS_DEFAULT=16 \
+
 common_c_includes := \
 	$(LOCAL_PATH)/src \
 	$(LOCAL_PATH)/include \
diff --git a/include/jemalloc/internal/chunk.h b/include/jemalloc/internal/chunk.h
index 47bbccd..f3bfbe0 100644
--- a/include/jemalloc/internal/chunk.h
+++ b/include/jemalloc/internal/chunk.h
@@ -5,11 +5,7 @@
  * Size and alignment of memory chunks that are allocated by the OS's virtual
  * memory system.
  */
-#if defined(__ANDROID__)
-#define	LG_CHUNK_DEFAULT	20
-#else
 #define	LG_CHUNK_DEFAULT	22
-#endif
 
 /* Return the chunk address for allocation address a. */
 #define	CHUNK_ADDR2BASE(a)						\
diff --git a/include/jemalloc/internal/tcache.h b/include/jemalloc/internal/tcache.h
index c0d48b9..6712341 100644
--- a/include/jemalloc/internal/tcache.h
+++ b/include/jemalloc/internal/tcache.h
@@ -22,13 +22,25 @@
  *
  * This constant must be an even number.
  */
+#if defined(ANDROID_TCACHE_NSLOTS_SMALL_MAX)
+#define	TCACHE_NSLOTS_SMALL_MAX		ANDROID_TCACHE_NSLOTS_SMALL_MAX
+#else
 #define	TCACHE_NSLOTS_SMALL_MAX		200
+#endif
 
 /* Number of cache slots for large size classes. */
+#if defined(ANDROID_TCACHE_NSLOTS_LARGE)
+#define	TCACHE_NSLOTS_LARGE		ANDROID_TCACHE_NSLOTS_LARGE
+#else
 #define	TCACHE_NSLOTS_LARGE		20
+#endif
 
 /* (1U << opt_lg_tcache_max) is used to compute tcache_maxclass. */
+#if defined(ANDROID_LG_TCACHE_MAXCLASS_DEFAULT)
+#define	LG_TCACHE_MAXCLASS_DEFAULT	ANDROID_LG_TCACHE_MAXCLASS_DEFAULT
+#else
 #define	LG_TCACHE_MAXCLASS_DEFAULT	15
+#endif
 
 /*
  * TCACHE_GC_SWEEP is the approximate number of allocation events between
diff --git a/src/arena.c b/src/arena.c
index d3fe0fb..026c74a 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -868,14 +868,17 @@
 static inline void
 arena_maybe_purge(arena_t *arena)
 {
+#if !defined(ANDROID_ALWAYS_PURGE)
 	size_t npurgeable, threshold;
 
 	/* Don't purge if the option is disabled. */
 	if (opt_lg_dirty_mult < 0)
 		return;
+#endif
 	/* Don't purge if all dirty pages are already being purged. */
 	if (arena->ndirty <= arena->npurgatory)
 		return;
+#if !defined(ANDROID_ALWAYS_PURGE)
 	npurgeable = arena->ndirty - arena->npurgatory;
 	threshold = (arena->nactive >> opt_lg_dirty_mult);
 	/*
@@ -884,6 +887,7 @@
 	 */
 	if (npurgeable <= threshold)
 		return;
+#endif
 
 	arena_purge(arena, false);
 }
diff --git a/src/jemalloc.c b/src/jemalloc.c
index baff69d..7e7aaf4 100644
--- a/src/jemalloc.c
+++ b/src/jemalloc.c
@@ -826,6 +826,14 @@
 		else
 			opt_narenas = 1;
 	}
+#if defined(ANDROID_MAX_ARENAS)
+	/* Never create more than MAX_ARENAS arenas regardless of num_cpus.
+	 * Extra arenas use more PSS and are not very useful unless
+	 * lots of threads are allocing/freeing at the same time.
+	 */
+	if (opt_narenas > ANDROID_MAX_ARENAS)
+		opt_narenas = ANDROID_MAX_ARENAS;
+#endif
 	narenas_auto = opt_narenas;
 	/*
 	 * Make sure that the arenas array can be allocated.  In practice, this