diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index 586002daef563c54e53aa825dfe5e62683e6ebd1..97e03266ebe06d1efb48cc91d4ee6443986c39c7 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -35,6 +35,7 @@
 #include "clang/Basic/TargetInfo.h"
 #include "clang/Basic/Diagnostic.h"
 #include "llvm/ADT/StringSet.h"
+#include "llvm/Support/Atomic.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Host.h"
 #include "llvm/Support/Path.h"
@@ -85,7 +86,7 @@ const unsigned DefaultPreambleRebuildInterval = 5;
 /// \brief Tracks the number of ASTUnit objects that are currently active.
 ///
 /// Used for debugging purposes only.
-static unsigned ActiveASTUnitObjects;
+static llvm::sys::cas_flag ActiveASTUnitObjects;
 
 ASTUnit::ASTUnit(bool _MainFileIsAST)
   : CaptureDiagnostics(false), MainFileIsAST(_MainFileIsAST), 
@@ -98,7 +99,7 @@ ASTUnit::ASTUnit(bool _MainFileIsAST)
     CacheCodeCompletionCoolDown(0),
     UnsafeToFree(false) { 
   if (getenv("LIBCLANG_OBJTRACKING")) {
-    ++ActiveASTUnitObjects;
+    llvm::sys::AtomicIncrement(&ActiveASTUnitObjects);
     fprintf(stderr, "+++ %d translation units\n", ActiveASTUnitObjects);
   }    
 }
@@ -129,7 +130,7 @@ ASTUnit::~ASTUnit() {
   ClearCachedCompletionResults();  
   
   if (getenv("LIBCLANG_OBJTRACKING")) {
-    --ActiveASTUnitObjects;
+    llvm::sys::AtomicDecrement(&ActiveASTUnitObjects);
     fprintf(stderr, "--- %d translation units\n", ActiveASTUnitObjects);
   }    
 }
diff --git a/clang/tools/libclang/CIndexCodeCompletion.cpp b/clang/tools/libclang/CIndexCodeCompletion.cpp
index 7441f4fa1d03bd078e8a2b8ad8036fef8d5be57c..02e45052aba1c391cff66fe2a5e77e06722f9782 100644
--- a/clang/tools/libclang/CIndexCodeCompletion.cpp
+++ b/clang/tools/libclang/CIndexCodeCompletion.cpp
@@ -24,6 +24,7 @@
 #include "clang/Sema/CodeCompleteConsumer.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/Atomic.h"
 #include "llvm/Support/CrashRecoveryContext.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Timer.h"
@@ -256,7 +257,7 @@ struct AllocatedCXCodeCompleteResults : public CXCodeCompleteResults {
 /// currently active.
 ///
 /// Used for debugging purposes only.
-static unsigned CodeCompletionResultObjects;
+static llvm::sys::cas_flag CodeCompletionResultObjects;
   
 AllocatedCXCodeCompleteResults::AllocatedCXCodeCompleteResults() 
   : CXCodeCompleteResults(),
@@ -265,7 +266,7 @@ AllocatedCXCodeCompleteResults::AllocatedCXCodeCompleteResults()
     FileMgr(FileSystemOpts),
     SourceMgr(*Diag, FileMgr) { 
   if (getenv("LIBCLANG_OBJTRACKING")) {
-    ++CodeCompletionResultObjects;
+    llvm::sys::AtomicIncrement(&CodeCompletionResultObjects);
     fprintf(stderr, "+++ %d completion results\n", CodeCompletionResultObjects);
   }    
 }
@@ -281,7 +282,7 @@ AllocatedCXCodeCompleteResults::~AllocatedCXCodeCompleteResults() {
     delete TemporaryBuffers[I];
 
   if (getenv("LIBCLANG_OBJTRACKING")) {
-    --CodeCompletionResultObjects;
+    llvm::sys::AtomicDecrement(&CodeCompletionResultObjects);
     fprintf(stderr, "--- %d completion results\n", CodeCompletionResultObjects);
   }    
 }