diff --git a/libc/bionic/jemalloc.h b/libc/bionic/jemalloc.h
index fceb323..f7e8770 100644
--- a/libc/bionic/jemalloc.h
+++ b/libc/bionic/jemalloc.h
@@ -26,6 +26,7 @@
 __BEGIN_DECLS
 
 struct mallinfo je_mallinfo();
+int je_mallopt(int, int);
 int je_iterate(uintptr_t, size_t, void (*)(uintptr_t, size_t, void*), void*);
 void je_malloc_disable();
 void je_malloc_enable();
diff --git a/libc/bionic/jemalloc_wrapper.cpp b/libc/bionic/jemalloc_wrapper.cpp
index e33d560..266b966 100644
--- a/libc/bionic/jemalloc_wrapper.cpp
+++ b/libc/bionic/jemalloc_wrapper.cpp
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include <malloc.h>
 #include <sys/param.h>
 #include <unistd.h>
 
@@ -46,3 +47,38 @@
   }
   return je_memalign(boundary, size);
 }
+
+int je_mallopt(int param, int value) {
+  // The only parameter we currently understand is M_DECAY_TIME.
+  if (param == M_DECAY_TIME) {
+    // Only support setting the value to 1 or 0.
+    ssize_t decay_time;
+    if (value) {
+      decay_time = 1;
+    } else {
+      decay_time = 0;
+    }
+    // First get the total number of arenas.
+    unsigned narenas;
+    size_t sz = sizeof(unsigned);
+    if (je_mallctl("arenas.narenas", &narenas, &sz, nullptr, 0) != 0) {
+      return 0;
+    }
+
+    // Set the decay time for any arenas that will be created in the future.
+    if (je_mallctl("arenas.decay_time", nullptr, nullptr, &decay_time, sizeof(decay_time)) != 0) {
+      return 0;
+    }
+
+    // Change the decay on the already existing arenas.
+    char buffer[100];
+    for (unsigned i = 0; i < narenas; i++) {
+      snprintf(buffer, sizeof(buffer), "arena.%d.decay_time", i);
+      if (je_mallctl(buffer, nullptr, nullptr, &decay_time, sizeof(decay_time)) != 0) {
+        break;
+      }
+    }
+    return 1;
+  }
+  return 0;
+}
diff --git a/libc/bionic/malloc_common.cpp b/libc/bionic/malloc_common.cpp
index 18c998d..1f201d1 100644
--- a/libc/bionic/malloc_common.cpp
+++ b/libc/bionic/malloc_common.cpp
@@ -68,6 +68,7 @@
     Malloc(iterate),
     Malloc(malloc_disable),
     Malloc(malloc_enable),
+    Malloc(mallopt),
   };
 
 // In a VM process, this is set to 1 after fork()ing out of zygote.
@@ -101,6 +102,14 @@
   return Malloc(mallinfo)();
 }
 
+extern "C" int mallopt(int param, int value) {
+  auto _mallopt = __libc_globals->malloc_dispatch.mallopt;
+  if (__predict_false(_mallopt != nullptr)) {
+    return _mallopt(param, value);
+  }
+  return Malloc(mallopt)(param, value);
+}
+
 extern "C" void* malloc(size_t bytes) {
   auto _malloc = __libc_globals->malloc_dispatch.malloc;
   if (__predict_false(_malloc != nullptr)) {
@@ -247,6 +256,10 @@
                                           prefix, "mallinfo")) {
     return false;
   }
+  if (!InitMallocFunction<MallocMallopt>(malloc_impl_handler, &table->mallopt,
+                                         prefix, "mallopt")) {
+    return false;
+  }
   if (!InitMallocFunction<MallocMalloc>(malloc_impl_handler, &table->malloc,
                                         prefix, "malloc")) {
     return false;
diff --git a/libc/include/malloc.h b/libc/include/malloc.h
index 412e3f0..db5da04 100644
--- a/libc/include/malloc.h
+++ b/libc/include/malloc.h
@@ -77,6 +77,11 @@
  */
 int malloc_info(int, FILE*) __INTRODUCED_IN(23);
 
+/* mallopt options */
+#define M_DECAY_TIME -100
+
+int mallopt(int, int) __INTRODUCED_IN(26);
+
 __END_DECLS
 
 #endif  /* LIBC_INCLUDE_MALLOC_H_ */
diff --git a/libc/libc.arm.map b/libc/libc.arm.map
index 7500742..4654f99 100644
--- a/libc/libc.arm.map
+++ b/libc/libc.arm.map
@@ -1551,4 +1551,5 @@
     malloc_disable;
     malloc_enable;
     malloc_iterate;
+    mallopt;
 } LIBC_O;
diff --git a/libc/libc.arm64.map b/libc/libc.arm64.map
index 9875eda..2c04e4d 100644
--- a/libc/libc.arm64.map
+++ b/libc/libc.arm64.map
@@ -1268,4 +1268,5 @@
     malloc_disable;
     malloc_enable;
     malloc_iterate;
+    mallopt;
 } LIBC_O;
diff --git a/libc/libc.mips.map b/libc/libc.mips.map
index 93d31a7..f68f1c5 100644
--- a/libc/libc.mips.map
+++ b/libc/libc.mips.map
@@ -1392,4 +1392,5 @@
     malloc_disable;
     malloc_enable;
     malloc_iterate;
+    mallopt;
 } LIBC_O;
diff --git a/libc/libc.mips64.map b/libc/libc.mips64.map
index 9875eda..2c04e4d 100644
--- a/libc/libc.mips64.map
+++ b/libc/libc.mips64.map
@@ -1268,4 +1268,5 @@
     malloc_disable;
     malloc_enable;
     malloc_iterate;
+    mallopt;
 } LIBC_O;
diff --git a/libc/libc.x86.map b/libc/libc.x86.map
index 08ef8be..bea2fe9 100644
--- a/libc/libc.x86.map
+++ b/libc/libc.x86.map
@@ -1391,4 +1391,5 @@
     malloc_disable;
     malloc_enable;
     malloc_iterate;
+    mallopt;
 } LIBC_O;
diff --git a/libc/libc.x86_64.map b/libc/libc.x86_64.map
index 9875eda..2c04e4d 100644
--- a/libc/libc.x86_64.map
+++ b/libc/libc.x86_64.map
@@ -1268,4 +1268,5 @@
     malloc_disable;
     malloc_enable;
     malloc_iterate;
+    mallopt;
 } LIBC_O;
diff --git a/libc/malloc_debug/malloc_debug.cpp b/libc/malloc_debug/malloc_debug.cpp
index addb5d4..014d385 100644
--- a/libc/malloc_debug/malloc_debug.cpp
+++ b/libc/malloc_debug/malloc_debug.cpp
@@ -77,6 +77,7 @@
 void* debug_realloc(void* pointer, size_t bytes);
 void* debug_calloc(size_t nmemb, size_t bytes);
 struct mallinfo debug_mallinfo();
+int debug_mallopt(int param, int value);
 int debug_posix_memalign(void** memptr, size_t alignment, size_t size);
 int debug_iterate(uintptr_t base, size_t size,
     void (*callback)(uintptr_t base, size_t size, void* arg), void* arg);
@@ -639,6 +640,10 @@
   return g_dispatch->mallinfo();
 }
 
+int debug_mallopt(int param, int value) {
+  return g_dispatch->mallopt(param, value);
+}
+
 int debug_posix_memalign(void** memptr, size_t alignment, size_t size) {
   if (DebugCallsDisabled()) {
     return g_dispatch->posix_memalign(memptr, alignment, size);
diff --git a/libc/malloc_debug/tests/malloc_debug_unit_tests.cpp b/libc/malloc_debug/tests/malloc_debug_unit_tests.cpp
index 219c21e..4fdba2e 100644
--- a/libc/malloc_debug/tests/malloc_debug_unit_tests.cpp
+++ b/libc/malloc_debug/tests/malloc_debug_unit_tests.cpp
@@ -58,6 +58,7 @@
 void debug_free_malloc_leak_info(uint8_t*);
 
 struct mallinfo debug_mallinfo();
+int debug_mallopt(int, int);
 
 #if defined(HAVE_DEPRECATED_MALLOC_FUNCS)
 void* debug_pvalloc(size_t);
@@ -128,6 +129,7 @@
   nullptr,
   nullptr,
   nullptr,
+  mallopt,
 };
 
 void VerifyAllocCalls() {
@@ -1474,6 +1476,20 @@
   ASSERT_STREQ("", getFakeLogPrint().c_str());
 }
 
+TEST_F(MallocDebugTest, debug_mallopt) {
+  Init("guard");
+
+  void* pointer = debug_malloc(150);
+  ASSERT_TRUE(pointer != nullptr);
+
+  EXPECT_EQ(0, debug_mallopt(-1000, 1));
+
+  debug_free(pointer);
+
+  ASSERT_STREQ("", getFakeLogBuf().c_str());
+  ASSERT_STREQ("", getFakeLogPrint().c_str());
+}
+
 TEST_F(MallocDebugTest, debug_posix_memalign) {
   Init("guard");
 
diff --git a/libc/private/bionic_malloc_dispatch.h b/libc/private/bionic_malloc_dispatch.h
index 02a092f..cdae466 100644
--- a/libc/private/bionic_malloc_dispatch.h
+++ b/libc/private/bionic_malloc_dispatch.h
@@ -45,6 +45,7 @@
 typedef int (*MallocIterate)(uintptr_t, size_t, void (*)(uintptr_t, size_t, void*), void*);
 typedef void (*MallocMallocDisable)();
 typedef void (*MallocMallocEnable)();
+typedef int (*MallocMallopt)(int, int);
 
 #if defined(HAVE_DEPRECATED_MALLOC_FUNCS)
 typedef void* (*MallocPvalloc)(size_t);
@@ -69,6 +70,7 @@
   MallocIterate iterate;
   MallocMallocDisable malloc_disable;
   MallocMallocEnable malloc_enable;
+  MallocMallopt mallopt;
 } __attribute__((aligned(32)));
 
 #endif
diff --git a/tests/malloc_test.cpp b/tests/malloc_test.cpp
index 8fba1c4..a7b9d52 100644
--- a/tests/malloc_test.cpp
+++ b/tests/malloc_test.cpp
@@ -500,3 +500,10 @@
   delete[] values_64;
   delete[] values_ldouble;
 }
+
+TEST(malloc, mallopt_smoke) {
+  errno = 0;
+  ASSERT_EQ(0, mallopt(-1000, 1));
+  // mallopt doesn't set errno.
+  ASSERT_EQ(0, errno);
+}