diff --git a/xpcom/base/nsTraceRefcnt.cpp b/xpcom/base/nsTraceRefcnt.cpp
index e00d634ddaf..ffa6f071f8b 100644
--- a/xpcom/base/nsTraceRefcnt.cpp
+++ b/xpcom/base/nsTraceRefcnt.cpp
@@ -17,8 +17,10 @@
  * Netscape Communications Corporation.  All Rights Reserved.
  */
 #include "nsISupports.h"
+#include "nsVoidArray.h"
 #include "prprf.h"
 #include "prlog.h"
+#include "plstr.h"
 
 #if defined(_WIN32)
 #include <windows.h>
@@ -542,3 +544,99 @@ nsTraceRefcnt::DemangleSymbol(const char * aSymbol,
 }
 #endif // __linux__
 
+//----------------------------------------------------------------------
+
+#ifdef DEBUG
+
+struct CtorEntry {
+  const char* type;
+  mozCtorDtorCounter* counter;
+};
+
+nsVoidArray* nsTraceRefcnt::mCtors;
+
+void
+nsTraceRefcnt::RegisterCtor(const char* aType,
+                            mozCtorDtorCounter* aCounterAddr)
+{
+  if (!mCtors) {
+    mCtors = new nsVoidArray();
+    if (!mCtors) {
+      return;
+    }
+  }
+  CtorEntry* e = new CtorEntry();
+  if (!e) {
+    return;
+  }
+  e->type = aType;
+  e->counter = aCounterAddr;
+  mCtors->AppendElement(e);
+}
+
+void
+nsTraceRefcnt::UnregisterCtor(const char* aType)
+{
+  if (mCtors) {
+    PRInt32 i, n = mCtors->Count();
+    for (i = 0; i < n; i++) {
+      CtorEntry* e = (CtorEntry*) mCtors->ElementAt(i);
+      if (0 == PL_strcmp(e->type, aType)) {
+        delete e;
+        mCtors->RemoveElementAt(i);
+        break;
+      }
+    }
+  }
+}
+
+void
+nsTraceRefcnt::DumpLeaks(FILE* out)
+{
+  if (mCtors) {
+    PRBool haveLeaks = PR_FALSE;
+    PRInt32 i, n = mCtors->Count();
+    for (i = 0; i < n; i++) {
+      CtorEntry* e = (CtorEntry*) mCtors->ElementAt(i);
+      if (e) {
+        mozCtorDtorCounter* cdc = e->counter;
+        if (cdc) {
+          if (cdc->ctors != cdc->dtors) {
+            haveLeaks = PR_TRUE;
+            break;
+          }
+        }
+      }
+    }
+    if (haveLeaks) {
+      fprintf(out, "*** There are memory leaks:\n");
+      fprintf(out, "%-40s %-15s %s\n", "Type", "# created", "# leaked");
+      fprintf(out, "%-40s %-15s %s\n", "----", "---------", "--------");
+
+      for (i = 0; i < n; i++) {
+        CtorEntry* e = (CtorEntry*) mCtors->ElementAt(i);
+        if (e && e->counter) {
+          mozCtorDtorCounter* cdc = e->counter;
+          if (cdc->ctors != cdc->dtors) {
+            fprintf(out, "%-40s %-15d %d\n", e->type, cdc->ctors,
+                    cdc->ctors - cdc->dtors);
+          }
+        }
+      }
+    }
+  }
+}
+
+void
+nsTraceRefcnt::FlushCtorRegistry(void)
+{
+  if (mCtors) {
+    PRInt32 i, n = mCtors->Count();
+    for (i = 0; i < n; i++) {
+      CtorEntry* e = (CtorEntry*) mCtors->ElementAt(i);
+      delete e;
+    }
+    delete mCtors;
+  }
+}
+#endif /* DEBUG */
diff --git a/xpcom/base/nsTraceRefcnt.h b/xpcom/base/nsTraceRefcnt.h
index 2424a0f2e6b..d4967e82192 100644
--- a/xpcom/base/nsTraceRefcnt.h
+++ b/xpcom/base/nsTraceRefcnt.h
@@ -20,6 +20,16 @@
 #define nsTraceRefcnt_h___
 
 #include "nsCom.h"
+#include <stdio.h>
+
+class nsVoidArray;
+
+#ifdef DEBUG
+struct mozCtorDtorCounter {
+  PRInt32 ctors;
+  PRInt32 dtors;
+};
+#endif
 
 /**
  * This class is used to support tracing (and logging using nspr) of
@@ -71,6 +81,63 @@ public:
                                 const char* aFile,
                                 int aLine);
 
+#ifdef DEBUG
+  /**
+   * Register a constructor with the xpcom library. This records the
+   * type name and the address of the counter so that later on when
+   * DumpLeaks is called, we can print out those objects ctors whose
+   * counter is not zero (the ones that have live object references
+   * still out there)
+   */
+  static NS_COM void RegisterCtor(const char* aType,
+                                  mozCtorDtorCounter* aCounterAddr);
+
+  static NS_COM void UnregisterCtor(const char* aType);
+
+  /**
+   * Dump the leaking constructors out.
+   */
+  static NS_COM void DumpLeaks(FILE* out);
+
+  /**
+   * Erase the ctor registration data.
+   */
+  static NS_COM void FlushCtorRegistry(void);
+#endif
+
+protected:
+#ifdef DEBUG
+  static nsVoidArray* mCtors;
+#endif
 };
 
+//----------------------------------------------------------------------
+
+#ifdef DEBUG
+
+#define MOZ_DECL_CTOR(_type)                  \
+  static mozCtorDtorCounter gCounter_##_type
+
+#define MOZ_CTOR(_type)                                     \
+PR_BEGIN_MACRO                                              \
+  if (0 == gCounter_##_type . ctors) {                      \
+    nsTraceRefcnt::RegisterCtor(#_type, &gCounter_##_type); \
+  }                                                         \
+  gCounter_##_type . ctors++;                               \
+PR_END_MACRO
+
+#define MOZ_DTOR(_type)        \
+PR_BEGIN_MACRO                 \
+  gCounter_##_type . dtors ++; \
+PR_END_MACRO
+
+#else
+
+#define MOZ_REG_CTOR(_type,_counter)
+#define MOZ_DECL_CTOR_(type)
+#define MOZ_CTOR(_type)
+#define MOZ_DTOR(_type)
+
+#endif /* DEBUG */
+
 #endif /* nsTraceRefcnt_h___ */
diff --git a/xpcom/base/nsTraceRefcntImpl.cpp b/xpcom/base/nsTraceRefcntImpl.cpp
index e00d634ddaf..ffa6f071f8b 100644
--- a/xpcom/base/nsTraceRefcntImpl.cpp
+++ b/xpcom/base/nsTraceRefcntImpl.cpp
@@ -17,8 +17,10 @@
  * Netscape Communications Corporation.  All Rights Reserved.
  */
 #include "nsISupports.h"
+#include "nsVoidArray.h"
 #include "prprf.h"
 #include "prlog.h"
+#include "plstr.h"
 
 #if defined(_WIN32)
 #include <windows.h>
@@ -542,3 +544,99 @@ nsTraceRefcnt::DemangleSymbol(const char * aSymbol,
 }
 #endif // __linux__
 
+//----------------------------------------------------------------------
+
+#ifdef DEBUG
+
+struct CtorEntry {
+  const char* type;
+  mozCtorDtorCounter* counter;
+};
+
+nsVoidArray* nsTraceRefcnt::mCtors;
+
+void
+nsTraceRefcnt::RegisterCtor(const char* aType,
+                            mozCtorDtorCounter* aCounterAddr)
+{
+  if (!mCtors) {
+    mCtors = new nsVoidArray();
+    if (!mCtors) {
+      return;
+    }
+  }
+  CtorEntry* e = new CtorEntry();
+  if (!e) {
+    return;
+  }
+  e->type = aType;
+  e->counter = aCounterAddr;
+  mCtors->AppendElement(e);
+}
+
+void
+nsTraceRefcnt::UnregisterCtor(const char* aType)
+{
+  if (mCtors) {
+    PRInt32 i, n = mCtors->Count();
+    for (i = 0; i < n; i++) {
+      CtorEntry* e = (CtorEntry*) mCtors->ElementAt(i);
+      if (0 == PL_strcmp(e->type, aType)) {
+        delete e;
+        mCtors->RemoveElementAt(i);
+        break;
+      }
+    }
+  }
+}
+
+void
+nsTraceRefcnt::DumpLeaks(FILE* out)
+{
+  if (mCtors) {
+    PRBool haveLeaks = PR_FALSE;
+    PRInt32 i, n = mCtors->Count();
+    for (i = 0; i < n; i++) {
+      CtorEntry* e = (CtorEntry*) mCtors->ElementAt(i);
+      if (e) {
+        mozCtorDtorCounter* cdc = e->counter;
+        if (cdc) {
+          if (cdc->ctors != cdc->dtors) {
+            haveLeaks = PR_TRUE;
+            break;
+          }
+        }
+      }
+    }
+    if (haveLeaks) {
+      fprintf(out, "*** There are memory leaks:\n");
+      fprintf(out, "%-40s %-15s %s\n", "Type", "# created", "# leaked");
+      fprintf(out, "%-40s %-15s %s\n", "----", "---------", "--------");
+
+      for (i = 0; i < n; i++) {
+        CtorEntry* e = (CtorEntry*) mCtors->ElementAt(i);
+        if (e && e->counter) {
+          mozCtorDtorCounter* cdc = e->counter;
+          if (cdc->ctors != cdc->dtors) {
+            fprintf(out, "%-40s %-15d %d\n", e->type, cdc->ctors,
+                    cdc->ctors - cdc->dtors);
+          }
+        }
+      }
+    }
+  }
+}
+
+void
+nsTraceRefcnt::FlushCtorRegistry(void)
+{
+  if (mCtors) {
+    PRInt32 i, n = mCtors->Count();
+    for (i = 0; i < n; i++) {
+      CtorEntry* e = (CtorEntry*) mCtors->ElementAt(i);
+      delete e;
+    }
+    delete mCtors;
+  }
+}
+#endif /* DEBUG */
diff --git a/xpcom/base/nsTraceRefcntImpl.h b/xpcom/base/nsTraceRefcntImpl.h
index 2424a0f2e6b..d4967e82192 100644
--- a/xpcom/base/nsTraceRefcntImpl.h
+++ b/xpcom/base/nsTraceRefcntImpl.h
@@ -20,6 +20,16 @@
 #define nsTraceRefcnt_h___
 
 #include "nsCom.h"
+#include <stdio.h>
+
+class nsVoidArray;
+
+#ifdef DEBUG
+struct mozCtorDtorCounter {
+  PRInt32 ctors;
+  PRInt32 dtors;
+};
+#endif
 
 /**
  * This class is used to support tracing (and logging using nspr) of
@@ -71,6 +81,63 @@ public:
                                 const char* aFile,
                                 int aLine);
 
+#ifdef DEBUG
+  /**
+   * Register a constructor with the xpcom library. This records the
+   * type name and the address of the counter so that later on when
+   * DumpLeaks is called, we can print out those objects ctors whose
+   * counter is not zero (the ones that have live object references
+   * still out there)
+   */
+  static NS_COM void RegisterCtor(const char* aType,
+                                  mozCtorDtorCounter* aCounterAddr);
+
+  static NS_COM void UnregisterCtor(const char* aType);
+
+  /**
+   * Dump the leaking constructors out.
+   */
+  static NS_COM void DumpLeaks(FILE* out);
+
+  /**
+   * Erase the ctor registration data.
+   */
+  static NS_COM void FlushCtorRegistry(void);
+#endif
+
+protected:
+#ifdef DEBUG
+  static nsVoidArray* mCtors;
+#endif
 };
 
+//----------------------------------------------------------------------
+
+#ifdef DEBUG
+
+#define MOZ_DECL_CTOR(_type)                  \
+  static mozCtorDtorCounter gCounter_##_type
+
+#define MOZ_CTOR(_type)                                     \
+PR_BEGIN_MACRO                                              \
+  if (0 == gCounter_##_type . ctors) {                      \
+    nsTraceRefcnt::RegisterCtor(#_type, &gCounter_##_type); \
+  }                                                         \
+  gCounter_##_type . ctors++;                               \
+PR_END_MACRO
+
+#define MOZ_DTOR(_type)        \
+PR_BEGIN_MACRO                 \
+  gCounter_##_type . dtors ++; \
+PR_END_MACRO
+
+#else
+
+#define MOZ_REG_CTOR(_type,_counter)
+#define MOZ_DECL_CTOR_(type)
+#define MOZ_CTOR(_type)
+#define MOZ_DTOR(_type)
+
+#endif /* DEBUG */
+
 #endif /* nsTraceRefcnt_h___ */