diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index 80ce522..fb93fca 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -81,6 +81,11 @@
 /// preamble.
 const unsigned DefaultPreambleRebuildInterval = 5;
 
+/// \brief Tracks the number of ASTUnit objects that are currently active.
+///
+/// Used for debugging purposes only.
+static unsigned ActiveASTUnitObjects;
+
 ASTUnit::ASTUnit(bool _MainFileIsAST)
   : CaptureDiagnostics(false), MainFileIsAST(_MainFileIsAST), 
     CompleteTranslationUnit(true), WantTiming(getenv("LIBCLANG_TIMING")),
@@ -91,6 +96,10 @@
     NumTopLevelDeclsAtLastCompletionCache(0),
     CacheCodeCompletionCoolDown(0),
     UnsafeToFree(false) { 
+  if (getenv("LIBCLANG_OBJTRACKING")) {
+    ++ActiveASTUnitObjects;
+    fprintf(stderr, "+++ %d translation units\n", ActiveASTUnitObjects);
+  }    
 }
 
 ASTUnit::~ASTUnit() {
@@ -117,6 +126,11 @@
   delete PreambleBuffer;
 
   ClearCachedCompletionResults();  
+  
+  if (getenv("LIBCLANG_OBJTRACKING")) {
+    --ActiveASTUnitObjects;
+    fprintf(stderr, "--- %d translation units\n", ActiveASTUnitObjects);
+  }    
 }
 
 void ASTUnit::CleanTemporaryFiles() {