diff --git a/base/util.cc b/base/util.cc
index 0c9d4ddb59..2169aad090 100644
--- a/base/util.cc
+++ b/base/util.cc
@@ -86,4 +86,32 @@ int64 WallTimer::GetInMs() const {
   return local_sum_usec / kMilliSecInMicroSec;
 #endif
 }
+
+// GetUsedMemory
+
+#if defined(__APPLE__) && defined(__GNUC__)
+#include <mach/mach_init.h>
+#include <mach/task.h>
+
+int64 GetMemoryUsage () {
+  task_t task = MACH_PORT_NULL;
+  struct task_basic_info t_info;
+  mach_msg_type_number_t t_info_count = TASK_BASIC_INFO_COUNT;
+
+  if (KERN_SUCCESS != task_info(mach_task_self(),
+                                TASK_BASIC_INFO,
+                                (task_info_t)&t_info,
+                                &t_info_count)) {
+    return -1;
+  }
+  int64 resident_memory = t_info.resident_size;
+  //  int64 virtual_memory = t_info.virtual_size;
+  return resident_memory;
+}
+#else
+int64 GetMemoryUsage() {
+  return 0;
+}
+#endif
+
 }  // namespace operations_research
diff --git a/base/util.h b/base/util.h
index 1ac5cb2b12..5e85bf1087 100644
--- a/base/util.h
+++ b/base/util.h
@@ -170,6 +170,8 @@ class WallTimer {
   DISALLOW_COPY_AND_ASSIGN(WallTimer);
 };
 
+int64 GetMemoryUsage();
+
 }  // namespace operations_research
 
 
diff --git a/constraint_solver/constraint_solver.cc b/constraint_solver/constraint_solver.cc
index b15e031486..91d81a43e0 100644
--- a/constraint_solver/constraint_solver.cc
+++ b/constraint_solver/constraint_solver.cc
@@ -1258,13 +1258,9 @@ string Solver::DebugString() const {
 }
 
 int64 Solver::MemoryUsage() {
-  // FIXME: Implement the real thing.
-     return 0ll;
-
+  return GetMemoryUsage();
 }
 
-
-
 int64 Solver::wall_time() const {
   return timer_->GetInMs();
 }
diff --git a/constraint_solver/search.cc b/constraint_solver/search.cc
index 5fc205abd9..9ab9b79243 100644
--- a/constraint_solver/search.cc
+++ b/constraint_solver/search.cc
@@ -205,8 +205,16 @@ void SearchLog::OutputLine(const string& line) {
 }
 
 string SearchLog::MemoryUsage() {
-  return StringPrintf("memory used = %" GG_LL_FORMAT "d", Solver::MemoryUsage());
-
+  int64 memory_usage = Solver::MemoryUsage();
+  if (memory_usage > 0x200000) {
+    return StringPrintf("memory used = %.2lf MB",
+                        memory_usage  * 1.0 / 1024 / 1024);
+  } else if (memory_usage > 0x1000) {
+    return StringPrintf("memory used = %" GG_LL_FORMAT "d KB",
+                        memory_usage / 1024);
+  } else {
+    return StringPrintf("memory used = %" GG_LL_FORMAT "d", memory_usage);
+  }
 }
 
 SearchMonitor* Solver::MakeSearchLog(int period) {