diff --git a/include/system/system.h b/include/system/system.h
index dc7628357a..a7effe7dfd 100644
--- a/include/system/system.h
+++ b/include/system/system.h
@@ -50,9 +50,11 @@ extern QEMUClockType rtc_clock;
 typedef enum {
     MLOCK_OFF = 0,
     MLOCK_ON,
+    MLOCK_ON_FAULT,
 } MlockState;
 
 bool should_mlock(MlockState);
+bool is_mlock_on_fault(MlockState);
 
 extern MlockState mlock_state;
 
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 04068ee039..5d3edfcfec 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -652,7 +652,7 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis)
     }
 
     if (should_mlock(mlock_state)) {
-        if (os_mlock(false) < 0) {
+        if (os_mlock(is_mlock_on_fault(mlock_state)) < 0) {
             error_report("mlock: %s", strerror(errno));
             /*
              * It doesn't feel right to fail at this point, we have a valid
diff --git a/qemu-options.hx b/qemu-options.hx
index 1b26ad53bd..61270e3206 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4632,21 +4632,25 @@ SRST
 ERST
 
 DEF("overcommit", HAS_ARG, QEMU_OPTION_overcommit,
-    "-overcommit [mem-lock=on|off][cpu-pm=on|off]\n"
+    "-overcommit [mem-lock=on|off|on-fault][cpu-pm=on|off]\n"
     "                run qemu with overcommit hints\n"
-    "                mem-lock=on|off controls memory lock support (default: off)\n"
+    "                mem-lock=on|off|on-fault controls memory lock support (default: off)\n"
     "                cpu-pm=on|off controls cpu power management (default: off)\n",
     QEMU_ARCH_ALL)
 SRST
-``-overcommit mem-lock=on|off``
+``-overcommit mem-lock=on|off|on-fault``
   \ 
 ``-overcommit cpu-pm=on|off``
     Run qemu with hints about host resource overcommit. The default is
     to assume that host overcommits all resources.
 
     Locking qemu and guest memory can be enabled via ``mem-lock=on``
-    (disabled by default). This works when host memory is not
-    overcommitted and reduces the worst-case latency for guest.
+    or ``mem-lock=on-fault`` (disabled by default). This works when
+    host memory is not overcommitted and reduces the worst-case latency for
+    guest. The on-fault option is better for reducing the memory footprint
+    since it makes allocations lazy, but the pages still get locked in place
+    once faulted by the guest or QEMU. Note that the two options are mutually
+    exclusive.
 
     Guest ability to manage power state of host cpus (increasing latency
     for other processes on the same host cpu, but decreasing latency for
diff --git a/system/globals.c b/system/globals.c
index adeff38348..316623bd20 100644
--- a/system/globals.c
+++ b/system/globals.c
@@ -33,7 +33,12 @@
 
 bool should_mlock(MlockState state)
 {
-    return state == MLOCK_ON;
+    return state == MLOCK_ON || state == MLOCK_ON_FAULT;
+}
+
+bool is_mlock_on_fault(MlockState state)
+{
+    return state == MLOCK_ON_FAULT;
 }
 
 enum vga_retrace_method vga_retrace_method = VGA_RETRACE_DUMB;
diff --git a/system/vl.c b/system/vl.c
index 2895824c1a..3c0fa2ff64 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -351,7 +351,7 @@ static QemuOptsList qemu_overcommit_opts = {
     .desc = {
         {
             .name = "mem-lock",
-            .type = QEMU_OPT_BOOL,
+            .type = QEMU_OPT_STRING,
         },
         {
             .name = "cpu-pm",
@@ -797,7 +797,7 @@ static QemuOptsList qemu_run_with_opts = {
 static void realtime_init(void)
 {
     if (should_mlock(mlock_state)) {
-        if (os_mlock(false) < 0) {
+        if (os_mlock(is_mlock_on_fault(mlock_state)) < 0) {
             error_report("locking memory failed");
             exit(1);
         }
@@ -1878,7 +1878,7 @@ static void object_option_parse(const char *str)
 static void overcommit_parse(const char *str)
 {
     QemuOpts *opts;
-    bool enable_mlock;
+    const char *mem_lock_opt;
 
     opts = qemu_opts_parse_noisily(qemu_find_opts("overcommit"),
                                    str, false);
@@ -1886,11 +1886,31 @@ static void overcommit_parse(const char *str)
         exit(1);
     }
 
-    enable_mlock = qemu_opt_get_bool(opts, "mem-lock",
-                                     should_mlock(mlock_state));
-    mlock_state = enable_mlock ? MLOCK_ON : MLOCK_OFF;
-
     enable_cpu_pm = qemu_opt_get_bool(opts, "cpu-pm", enable_cpu_pm);
+
+    mem_lock_opt = qemu_opt_get(opts, "mem-lock");
+    if (!mem_lock_opt) {
+        return;
+    }
+
+    if (strcmp(mem_lock_opt, "on") == 0) {
+        mlock_state = MLOCK_ON;
+        return;
+    }
+
+    if (strcmp(mem_lock_opt, "off") == 0) {
+        mlock_state = MLOCK_OFF;
+        return;
+    }
+
+    if (strcmp(mem_lock_opt, "on-fault") == 0) {
+        mlock_state = MLOCK_ON_FAULT;
+        return;
+    }
+
+    error_report("parameter 'mem-lock' expects one of "
+                 "'on', 'off', 'on-fault'");
+    exit(1);
 }
 
 /*