diff --git a/doc/jemalloc.xml.in b/doc/jemalloc.xml.in
index 895b2d4d..3f9ba201 100644
--- a/doc/jemalloc.xml.in
+++ b/doc/jemalloc.xml.in
@@ -1069,6 +1069,22 @@ mallctl("arena." STRINGIFY(MALLCTL_ARENAS_ALL) ".decay",
         for related dynamic control options.</para></listitem>
       </varlistentry>
 
+      <varlistentry id="opt.lg_extent_max_active_fit">
+        <term>
+          <mallctl>opt.lg_extent_max_active_fit</mallctl>
+          (<type>size_t</type>)
+          <literal>r-</literal>
+        </term>
+        <listitem><para>When reusing dirty extents, this determines the (log
+        base 2 of the) maximum ratio between the size of the active extent
+        selected (to split off from) and the size of the requested allocation.
+        This prevents the splitting of large active extents for smaller
+        allocations, which can reduce fragmentation over the long run
+        (especially for non-active extents).  Lower value may reduce
+        fragmentation, at the cost of extra active extents.  The default value
+        is 6, which gives a maximum ratio of 64 (2^6).</para></listitem>
+      </varlistentry>
+
       <varlistentry id="opt.stats_print">
         <term>
           <mallctl>opt.stats_print</mallctl>
diff --git a/include/jemalloc/internal/extent_externs.h b/include/jemalloc/internal/extent_externs.h
index 132d8903..a76d4e4a 100644
--- a/include/jemalloc/internal/extent_externs.h
+++ b/include/jemalloc/internal/extent_externs.h
@@ -6,9 +6,11 @@
 #include "jemalloc/internal/ph.h"
 #include "jemalloc/internal/rtree.h"
 
-extern rtree_t			extents_rtree;
-extern const extent_hooks_t	extent_hooks_default;
-extern mutex_pool_t		extent_mutex_pool;
+extern size_t opt_lg_extent_max_active_fit;
+
+extern rtree_t extents_rtree;
+extern const extent_hooks_t extent_hooks_default;
+extern mutex_pool_t extent_mutex_pool;
 
 extent_t *extent_alloc(tsdn_t *tsdn, arena_t *arena);
 void extent_dalloc(tsdn_t *tsdn, arena_t *arena, extent_t *extent);
diff --git a/include/jemalloc/internal/extent_types.h b/include/jemalloc/internal/extent_types.h
index 7efcd3a4..c0561d99 100644
--- a/include/jemalloc/internal/extent_types.h
+++ b/include/jemalloc/internal/extent_types.h
@@ -8,4 +8,10 @@ typedef struct extents_s extents_t;
 
 #define EXTENT_GROW_MAX_PIND (NPSIZES - 1)
 
+/*
+ * When reuse (and split) an active extent, (1U << opt_lg_extent_max_active_fit)
+ * is the max ratio between the size of the active extent and the new extent.
+ */
+#define LG_EXTENT_MAX_ACTIVE_FIT_DEFAULT 6
+
 #endif /* JEMALLOC_INTERNAL_EXTENT_TYPES_H */
diff --git a/src/ctl.c b/src/ctl.c
index 11cd68db..1fdb772d 100644
--- a/src/ctl.c
+++ b/src/ctl.c
@@ -95,6 +95,7 @@ CTL_PROTO(opt_zero)
 CTL_PROTO(opt_utrace)
 CTL_PROTO(opt_xmalloc)
 CTL_PROTO(opt_tcache)
+CTL_PROTO(opt_lg_extent_max_active_fit)
 CTL_PROTO(opt_lg_tcache_max)
 CTL_PROTO(opt_prof)
 CTL_PROTO(opt_prof_prefix)
@@ -293,6 +294,7 @@ static const ctl_named_node_t opt_node[] = {
 	{NAME("utrace"),	CTL(opt_utrace)},
 	{NAME("xmalloc"),	CTL(opt_xmalloc)},
 	{NAME("tcache"),	CTL(opt_tcache)},
+	{NAME("lg_extent_max_active_fit"), CTL(opt_lg_extent_max_active_fit)},
 	{NAME("lg_tcache_max"),	CTL(opt_lg_tcache_max)},
 	{NAME("prof"),		CTL(opt_prof)},
 	{NAME("prof_prefix"),	CTL(opt_prof_prefix)},
@@ -1597,6 +1599,8 @@ CTL_RO_NL_CGEN(config_fill, opt_zero, opt_zero, bool)
 CTL_RO_NL_CGEN(config_utrace, opt_utrace, opt_utrace, bool)
 CTL_RO_NL_CGEN(config_xmalloc, opt_xmalloc, opt_xmalloc, bool)
 CTL_RO_NL_GEN(opt_tcache, opt_tcache, bool)
+CTL_RO_NL_GEN(opt_lg_extent_max_active_fit, opt_lg_extent_max_active_fit,
+    size_t)
 CTL_RO_NL_GEN(opt_lg_tcache_max, opt_lg_tcache_max, ssize_t)
 CTL_RO_NL_CGEN(config_prof, opt_prof, opt_prof, bool)
 CTL_RO_NL_CGEN(config_prof, opt_prof_prefix, opt_prof_prefix, const char *)
diff --git a/src/extent.c b/src/extent.c
index 466e0b2a..548a93e2 100644
--- a/src/extent.c
+++ b/src/extent.c
@@ -17,6 +17,8 @@ rtree_t		extents_rtree;
 /* Keyed by the address of the extent_t being protected. */
 mutex_pool_t	extent_mutex_pool;
 
+size_t opt_lg_extent_max_active_fit = LG_EXTENT_MAX_ACTIVE_FIT_DEFAULT;
+
 static const bitmap_info_t extents_bitmap_info =
     BITMAP_INFO_INITIALIZER(NPSIZES+1);
 
@@ -369,6 +371,13 @@ extents_best_fit_locked(tsdn_t *tsdn, arena_t *arena, extents_t *extents,
 	pszind_t i = (pszind_t)bitmap_ffu(extents->bitmap, &extents_bitmap_info,
 	    (size_t)pind);
 	if (i < NPSIZES+1) {
+		/*
+		 * In order to reduce fragmentation, avoid reusing and splitting
+		 * large extents for much smaller sizes.
+		 */
+		if ((sz_pind2sz(i) >> opt_lg_extent_max_active_fit) > size) {
+			return NULL;
+		}
 		assert(!extent_heap_empty(&extents->heaps[i]));
 		extent_t *extent = extent_heap_first(&extents->heaps[i]);
 		assert(extent_size_get(extent) >= size);
diff --git a/src/jemalloc.c b/src/jemalloc.c
index f29fc7da..f4fd805e 100644
--- a/src/jemalloc.c
+++ b/src/jemalloc.c
@@ -1146,6 +1146,9 @@ malloc_conf_init(void) {
 				CONF_HANDLE_BOOL(opt_xmalloc, "xmalloc")
 			}
 			CONF_HANDLE_BOOL(opt_tcache, "tcache")
+			CONF_HANDLE_SIZE_T(opt_lg_extent_max_active_fit,
+			    "lg_extent_max_active_fit", 0,
+			    (sizeof(size_t) << 3), yes, yes, false)
 			CONF_HANDLE_SSIZE_T(opt_lg_tcache_max, "lg_tcache_max",
 			    -1, (sizeof(size_t) << 3) - 1)
 			if (strncmp("percpu_arena", k, klen) == 0) {
diff --git a/test/unit/mallctl.c b/test/unit/mallctl.c
index 94f801e3..4cfd981a 100644
--- a/test/unit/mallctl.c
+++ b/test/unit/mallctl.c
@@ -172,6 +172,7 @@ TEST_BEGIN(test_mallctl_opt) {
 	TEST_MALLCTL_OPT(bool, utrace, utrace);
 	TEST_MALLCTL_OPT(bool, xmalloc, xmalloc);
 	TEST_MALLCTL_OPT(bool, tcache, always);
+	TEST_MALLCTL_OPT(size_t, lg_extent_max_active_fit, always);
 	TEST_MALLCTL_OPT(size_t, lg_tcache_max, always);
 	TEST_MALLCTL_OPT(bool, prof, prof);
 	TEST_MALLCTL_OPT(const char *, prof_prefix, prof);