diff --git a/lib/Interpreter/CIFactory.cpp b/lib/Interpreter/CIFactory.cpp
index 0368a116..a18eea5b 100644
--- a/lib/Interpreter/CIFactory.cpp
+++ b/lib/Interpreter/CIFactory.cpp
@@ -726,6 +726,7 @@ namespace cling {
       stateCollector = new DeclCollector();
     // Set up the ASTConsumers
     CI->setASTConsumer(stateCollector);
+    CI->getASTContext().setASTMutationListener(stateCollector);
 
     // Set up Sema
     CodeCompleteConsumer* CCC = 0;
diff --git a/lib/Interpreter/DeclCollector.cpp b/lib/Interpreter/DeclCollector.cpp
index 0f064969..41cd7a1c 100644
--- a/lib/Interpreter/DeclCollector.cpp
+++ b/lib/Interpreter/DeclCollector.cpp
@@ -31,9 +31,25 @@ namespace cling {
     return D->isFromASTFile();
   }
 
+  bool DeclCollector::comesFromASTReader(const Decl* D) const {
+    // The operation is const but clang::DeclGroupRef doesn't allow us to
+    // express it.
+    return comesFromASTReader(DeclGroupRef(const_cast<Decl*>(D)));
+  }
+
   // pin the vtable here.
   DeclCollector::~DeclCollector() { }
 
+  void DeclCollector::AddedCXXImplicitMember(const CXXRecordDecl *RD,
+                                             const Decl *D) {
+    assert(D->isImplicit());
+    // We need to mark the decls coming from the modules
+    if (comesFromASTReader(RD) || comesFromASTReader(D)) {
+      Decl* implicitD = const_cast<Decl*>(D);
+      implicitD->addAttr(UsedAttr::CreateImplicit(implicitD->getASTContext()));
+    }
+  }
+
   bool DeclCollector::HandleTopLevelDecl(DeclGroupRef DGR) {
     Transaction::DelayCallInfo DCI(DGR, Transaction::kCCIHandleTopLevelDecl);
     m_CurTransaction->append(DCI);
diff --git a/lib/Interpreter/DeclCollector.h b/lib/Interpreter/DeclCollector.h
index 504e6b09..23c4d349 100644
--- a/lib/Interpreter/DeclCollector.h
+++ b/lib/Interpreter/DeclCollector.h
@@ -11,6 +11,7 @@
 #define CLING_DECL_COLLECTOR_H
 
 #include "clang/AST/ASTConsumer.h"
+#include "clang/AST/ASTMutationListener.h"
 #include "clang/Lex/PPCallbacks.h"
 
 namespace clang {
@@ -32,7 +33,9 @@ namespace cling {
   /// cling::DeclCollector is responsible for appending all the declarations
   /// seen by clang.
   ///
-  class DeclCollector: public clang::PPCallbacks, public clang::ASTConsumer  {
+  class DeclCollector: public clang::PPCallbacks,
+                       public clang::ASTMutationListener,
+                       public clang::ASTConsumer  {
   private:
     Transaction* m_CurTransaction;
 
@@ -40,11 +43,23 @@ namespace cling {
     /// file.
     ///
     bool comesFromASTReader(clang::DeclGroupRef DGR) const;
+    bool comesFromASTReader(const clang::Decl* D) const;
 
   public:
     DeclCollector() : m_CurTransaction(0){}
     virtual ~DeclCollector();
 
+    /// \name PPCallbacks overrides
+    /// Macro support
+    virtual void MacroDefined(const clang::Token &MacroNameTok,
+                              const clang::MacroDirective *MD);
+    /// \}
+
+    /// \name ASTMutationListeners overrides
+    virtual void AddedCXXImplicitMember(const clang::CXXRecordDecl *RD,
+                                        const clang::Decl *D);
+    /// \}
+
     /// \{
     /// \name ASTConsumer overrides
 
@@ -71,9 +86,6 @@ namespace cling {
 
     /// \}
 
-    /// Macro support
-    virtual void MacroDefined (const clang::Token &MacroNameTok,
-                               const clang::MacroDirective *MD);
     // dyn_cast/isa support
     static bool classof(const clang::ASTConsumer*) { return true; }
   };
diff --git a/lib/Interpreter/TransactionUnloader.cpp b/lib/Interpreter/TransactionUnloader.cpp
index 8ed09280..c369695e 100644
--- a/lib/Interpreter/TransactionUnloader.cpp
+++ b/lib/Interpreter/TransactionUnloader.cpp
@@ -64,6 +64,7 @@ namespace clang {
       Changed |= RemoveUnusedGlobalValue(*GV);
       // Collect all uses of globals by GV
       CollectAllUsesOfGlobals(GV);
+      FindUsedValues(*GV->getParent());
 
       // The first pass is to drop initializers of global vars which are dead.
       for (Globals::iterator I = VisitedGlobals.begin(),
@@ -108,6 +109,24 @@ namespace clang {
     }
 
   private:
+
+    /// Find values that are marked as llvm.used.
+    void FindUsedValues(const llvm::Module& m) {
+      for (const llvm::GlobalVariable& GV : m.globals()) {
+        if (!GV.getName().startswith("llvm.used"))
+          continue;
+
+        const llvm::ConstantArray* Inits
+          = cast<llvm::ConstantArray>(GV.getInitializer());
+
+        for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i) {
+          llvm::Value *Operand
+            = Inits->getOperand(i)->stripPointerCastsNoFollowAliases();
+          VisitedGlobals.erase(cast<llvm::GlobalValue>(Operand));
+        }
+
+      }
+    }
     /// CollectAllUsesOfGlobals - collects recursively all referenced globals by
     /// GV.
     void CollectAllUsesOfGlobals(llvm::GlobalValue *G) {