diff --git a/lldb/source/Plugins/LanguageRuntime/RenderScript/RenderScriptRuntime/RenderScriptx86ABIFixups.cpp b/lldb/source/Plugins/LanguageRuntime/RenderScript/RenderScriptRuntime/RenderScriptx86ABIFixups.cpp
--- a/lldb/source/Plugins/LanguageRuntime/RenderScript/RenderScriptRuntime/RenderScriptx86ABIFixups.cpp
+++ b/lldb/source/Plugins/LanguageRuntime/RenderScript/RenderScriptRuntime/RenderScriptx86ABIFixups.cpp
@@ -237,8 +237,7 @@
     llvm::AttributeList call_attribs = call_inst->getAttributes();
 
     // iterate over the argument attributes
-    for (unsigned I = call_attribs.index_begin(); I != call_attribs.index_end();
-         I++) {
+    for (unsigned I : call_attribs.indexes()) {
       // if this argument is passed by val
       if (call_attribs.hasAttributeAtIndex(I, llvm::Attribute::ByVal)) {
         // strip away the byval attribute
diff --git a/llvm/include/llvm/IR/Attributes.h b/llvm/include/llvm/IR/Attributes.h
--- a/llvm/include/llvm/IR/Attributes.h
+++ b/llvm/include/llvm/IR/Attributes.h
@@ -851,9 +851,32 @@
 
   unsigned getNumAttrSets() const;
 
-  /// Use these to iterate over the valid attribute indices.
-  unsigned index_begin() const { return AttributeList::FunctionIndex; }
-  unsigned index_end() const { return getNumAttrSets() - 1; }
+  // Implementation of indexes(). Produces iterators that wrap an index. Mostly
+  // to hide the awkwardness of unsigned wrapping when iterating over valid
+  // indexes.
+  struct index_iterator {
+    unsigned NumAttrSets;
+    index_iterator(int NumAttrSets) : NumAttrSets(NumAttrSets) {}
+    struct int_wrapper {
+      int_wrapper(unsigned i) : i(i) {}
+      unsigned i;
+      unsigned operator*() { return i; }
+      bool operator!=(const int_wrapper &Other) { return i != Other.i; }
+      int_wrapper &operator++() {
+        // This is expected to undergo unsigned wrapping since FunctionIndex is
+        // ~0 and that's where we start.
+        ++i;
+        return *this;
+      }
+    };
+
+    int_wrapper begin() { return int_wrapper(AttributeList::FunctionIndex); }
+
+    int_wrapper end() { return int_wrapper(NumAttrSets - 1); }
+  };
+
+  /// Use this to iterate over the valid attribute indexes.
+  index_iterator indexes() const { return index_iterator(getNumAttrSets()); }
 
   /// operator==/!= - Provide equality predicates.
   bool operator==(const AttributeList &RHS) const { return pImpl == RHS.pImpl; }
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -835,7 +835,7 @@
   SmallVector<uint64_t, 64> Record;
   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
     AttributeList AL = Attrs[i];
-    for (unsigned i = AL.index_begin(), e = AL.index_end(); i != e; ++i) {
+    for (unsigned i : AL.indexes()) {
       AttributeSet AS = AL.getAttributes(i);
       if (AS.hasAttributes())
         Record.push_back(VE.getAttributeGroupID({i, AS}));
diff --git a/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp b/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
--- a/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
+++ b/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
@@ -1039,7 +1039,7 @@
   }
 
   // Do lookups for all attribute groups.
-  for (unsigned i = PAL.index_begin(), e = PAL.index_end(); i != e; ++i) {
+  for (unsigned i : PAL.indexes()) {
     AttributeSet AS = PAL.getAttributes(i);
     if (!AS.hasAttributes())
       continue;
diff --git a/llvm/lib/IR/Attributes.cpp b/llvm/lib/IR/Attributes.cpp
--- a/llvm/lib/IR/Attributes.cpp
+++ b/llvm/lib/IR/Attributes.cpp
@@ -1527,7 +1527,7 @@
 void AttributeList::print(raw_ostream &O) const {
   O << "AttributeList[\n";
 
-  for (unsigned i = index_begin(), e = index_end(); i != e; ++i) {
+  for (unsigned i : indexes()) {
     if (!getAttributes(i).hasAttributes())
       continue;
     O << "  { ";
diff --git a/llvm/lib/Transforms/Utils/FunctionComparator.cpp b/llvm/lib/Transforms/Utils/FunctionComparator.cpp
--- a/llvm/lib/Transforms/Utils/FunctionComparator.cpp
+++ b/llvm/lib/Transforms/Utils/FunctionComparator.cpp
@@ -110,7 +110,7 @@
   if (int Res = cmpNumbers(L.getNumAttrSets(), R.getNumAttrSets()))
     return Res;
 
-  for (unsigned i = L.index_begin(), e = L.index_end(); i != e; ++i) {
+  for (unsigned i : L.indexes()) {
     AttributeSet LAS = L.getAttributes(i);
     AttributeSet RAS = R.getAttributes(i);
     AttributeSet::iterator LI = LAS.begin(), LE = LAS.end();
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceAttributes.cpp b/llvm/tools/llvm-reduce/deltas/ReduceAttributes.cpp
--- a/llvm/tools/llvm-reduce/deltas/ReduceAttributes.cpp
+++ b/llvm/tools/llvm-reduce/deltas/ReduceAttributes.cpp
@@ -84,8 +84,7 @@
                           AttrPtrVecVecTy &AttributeSetsToPreserve) {
     assert(AttributeSetsToPreserve.empty() && "Should not be sharing vectors.");
     AttributeSetsToPreserve.reserve(AL.getNumAttrSets());
-    for (unsigned SetIdx = AL.index_begin(), SetEndIdx = AL.index_end();
-         SetIdx != SetEndIdx; ++SetIdx) {
+    for (unsigned SetIdx : AL.indexes()) {
       AttrPtrIdxVecVecTy AttributesToPreserve;
       AttributesToPreserve.first = SetIdx;
       visitAttributeSet(AL.getAttributes(AttributesToPreserve.first),