diff --git a/llvm/include/llvm/Support/Annotation.h b/llvm/include/llvm/Support/Annotation.h
index 4a53ff59a99b..2be1c1061690 100644
--- a/llvm/include/llvm/Support/Annotation.h
+++ b/llvm/include/llvm/Support/Annotation.h
@@ -43,7 +43,9 @@ class AnnotationID {
   unsigned ID;
 
   AnnotationID();                             // Default ctor is disabled
-  inline AnnotationID(unsigned i) : ID(i) {}  // Only creatable from AnnMgr
+
+  // AnnotationID is only creatable from AnnMgr.
+  explicit inline AnnotationID(unsigned i) : ID(i) {}
 public:
   inline AnnotationID(const AnnotationID &A) : ID(A.ID) {}
 
@@ -67,7 +69,7 @@ class Annotation {
   AnnotationID ID;         // ID number, as obtained from AnnotationManager
   Annotation *Next;        // The next annotation in the linked list
 public:
-  inline Annotation(AnnotationID id) : ID(id), Next(0) {}
+  explicit inline Annotation(AnnotationID id) : ID(id), Next(0) {}
   virtual ~Annotation();  // Designed to be subclassed
 
   // getID - Return the unique ID# of this annotation
diff --git a/llvm/include/llvm/Support/CommandLine.h b/llvm/include/llvm/Support/CommandLine.h
index 1392e334ac52..0f804395c392 100644
--- a/llvm/include/llvm/Support/CommandLine.h
+++ b/llvm/include/llvm/Support/CommandLine.h
@@ -1316,7 +1316,7 @@ struct aliasopt {
 // exit is called.
 struct extrahelp {
   const char * morehelp;
-  extrahelp(const char* help);
+  explicit extrahelp(const char* help);
 };
 
 void PrintVersionMessage();
diff --git a/llvm/include/llvm/Support/ConstantRange.h b/llvm/include/llvm/Support/ConstantRange.h
index 6fb56b3b2573..2e477cf89984 100644
--- a/llvm/include/llvm/Support/ConstantRange.h
+++ b/llvm/include/llvm/Support/ConstantRange.h
@@ -44,7 +44,7 @@ class ConstantRange {
  public:
   /// Initialize a full (the default) or empty set for the specified bit width.
   ///
-  ConstantRange(uint32_t BitWidth, bool isFullSet = true);
+  explicit ConstantRange(uint32_t BitWidth, bool isFullSet = true);
 
   /// Initialize a range to hold the single specified value.
   ///
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index d1de88b7e24e..244dee393f60 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -262,7 +262,7 @@ class VISIBILITY_HIDDEN WorkListRemover :
   public SelectionDAG::DAGUpdateListener {
   DAGCombiner &DC;
 public:
-  WorkListRemover(DAGCombiner &dc) : DC(dc) {}
+  explicit WorkListRemover(DAGCombiner &dc) : DC(dc) {}
   
   virtual void NodeDeleted(SDNode *N) {
     DC.removeFromWorkList(N);
diff --git a/llvm/lib/Support/Annotation.cpp b/llvm/lib/Support/Annotation.cpp
index 9d5e5457d9a8..3ecc42f782e2 100644
--- a/llvm/lib/Support/Annotation.cpp
+++ b/llvm/lib/Support/Annotation.cpp
@@ -57,9 +57,9 @@ AnnotationID AnnotationManager::getID(const std::string &Name) {  // Name -> ID
   IDMapType::iterator I = IDMap->find(Name);
   if (I == IDMap->end()) {
     (*IDMap)[Name] = IDCounter++;   // Add a new element
-    return IDCounter-1;
+    return AnnotationID(IDCounter-1);
   }
-  return I->second;
+  return AnnotationID(I->second);
 }
 
 // getID - Name -> ID + registration of a factory function for demand driven
diff --git a/llvm/lib/Transforms/Scalar/PredicateSimplifier.cpp b/llvm/lib/Transforms/Scalar/PredicateSimplifier.cpp
index 388071d1e9ac..d0067b3302c6 100644
--- a/llvm/lib/Transforms/Scalar/PredicateSimplifier.cpp
+++ b/llvm/lib/Transforms/Scalar/PredicateSimplifier.cpp
@@ -1112,7 +1112,7 @@ namespace {
       else if (isa<ConstantPointerNull>(V))
         return ConstantRange(APInt::getNullValue(typeToWidth(V->getType())));
       else
-        return typeToWidth(V->getType());
+        return ConstantRange(typeToWidth(V->getType()));
     }
 
     // typeToWidth - returns the number of bits necessary to store a value of