diff --git a/llvm/lib/Support/Timer.cpp b/llvm/lib/Support/Timer.cpp
index 17fea8b..8023c50 100644
--- a/llvm/lib/Support/Timer.cpp
+++ b/llvm/lib/Support/Timer.cpp
@@ -5,6 +5,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "Support/Timer.h"
+#include "Support/CommandLine.h"
 #include <sys/resource.h>
 #include <sys/time.h>
 #include <sys/unistd.h>
@@ -15,6 +16,13 @@
 #include <algorithm>
 #include <functional>
 
+namespace {
+  cl::opt<bool>
+  TrackSpace("track-memory", cl::desc("Enable -time-passes memory "
+                                      "tracking (this may be slow)"),
+             cl::Hidden);
+}
+
 // getNumBytesToNotCount - This function is supposed to return the number of
 // bytes that are to be considered not allocated, even though malloc thinks they
 // are allocated.
@@ -65,8 +73,12 @@
 }
 
 static long getMemUsage() {
-  struct mallinfo MI = mallinfo();
-  return MI.uordblks/*+MI.hblkhd-getNumBytesToNotCount()*/;
+  if (TrackSpace) {
+    struct mallinfo MI = mallinfo();
+    return MI.uordblks/*+MI.hblkhd-getNumBytesToNotCount()*/;
+  } else {
+    return 0;
+  }
 }
 
 struct TimeRecord {