diff --git a/llvm/include/llvm/IR/AutoUpgrade.h b/llvm/include/llvm/IR/AutoUpgrade.h
--- a/llvm/include/llvm/IR/AutoUpgrade.h
+++ b/llvm/include/llvm/IR/AutoUpgrade.h
@@ -14,6 +14,7 @@
 #define LLVM_IR_AUTOUPGRADE_H
 
 #include "llvm/ADT/StringRef.h"
+#include <vector>
 
 namespace llvm {
   class AttrBuilder;
@@ -28,6 +29,9 @@
   class Type;
   class Value;
 
+  template <typename T> class OperandBundleDefT;
+  using OperandBundleDef = OperandBundleDefT<Value *>;
+
   /// This is a more granular function that simply checks an intrinsic function
   /// for upgrading, and returns true if it requires upgrading. It may return
   /// null in NewFn if the all calls to the original intrinsic function
@@ -99,6 +103,9 @@
   /// Upgrade attributes that changed format or kind.
   void UpgradeAttributes(AttrBuilder &B);
 
+  /// Upgrade operand bundles (without knowing about their user instruction).
+  void UpgradeOperandBundles(std::vector<OperandBundleDef> &OperandBundles);
+
 } // End llvm namespace
 
 #endif
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -5138,6 +5138,10 @@
         }
       }
 
+      // Upgrade the bundles if needed.
+      if (!OperandBundles.empty())
+        UpgradeOperandBundles(OperandBundles);
+
       I = InvokeInst::Create(FTy, Callee, NormalBB, UnwindBB, Ops,
                              OperandBundles);
       ResTypeID = getContainedTypeID(FTyID);
@@ -5235,6 +5239,10 @@
         }
       }
 
+      // Upgrade the bundles if needed.
+      if (!OperandBundles.empty())
+        UpgradeOperandBundles(OperandBundles);
+
       I = CallBrInst::Create(FTy, Callee, DefaultDest, IndirectDests, Args,
                              OperandBundles);
       ResTypeID = getContainedTypeID(FTyID);
@@ -5846,6 +5854,10 @@
         }
       }
 
+      // Upgrade the bundles if needed.
+      if (!OperandBundles.empty())
+        UpgradeOperandBundles(OperandBundles);
+
       I = CallInst::Create(FTy, Callee, Args, OperandBundles);
       ResTypeID = getContainedTypeID(FTyID);
       OperandBundles.clear();
diff --git a/llvm/lib/IR/AutoUpgrade.cpp b/llvm/lib/IR/AutoUpgrade.cpp
--- a/llvm/lib/IR/AutoUpgrade.cpp
+++ b/llvm/lib/IR/AutoUpgrade.cpp
@@ -4675,3 +4675,15 @@
       B.addAttribute(Attribute::NullPointerIsValid);
   }
 }
+
+void llvm::UpgradeOperandBundles(std::vector<OperandBundleDef> &Bundles) {
+
+  // clang.arc.attachedcall bundles are now required to have an operand.
+  // If they don't, it's okay to drop them entirely: when there is an operand,
+  // the "attachedcall" is meaningful and required, but without an operand,
+  // it's just a marker NOP.  Dropping it merely prevents an optimization.
+  erase_if(Bundles, [&](OperandBundleDef &OBD) {
+    return OBD.getTag() == "clang.arc.attachedcall" &&
+           OBD.inputs().empty();
+  });
+}
diff --git a/llvm/test/Bitcode/upgrade-arc-attachedcall-bundle.ll b/llvm/test/Bitcode/upgrade-arc-attachedcall-bundle.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Bitcode/upgrade-arc-attachedcall-bundle.ll
@@ -0,0 +1,23 @@
+; Test that nullary clang.arc.attachedcall operand bundles are "upgraded".
+
+; RUN: llvm-dis %s.bc -o - | FileCheck %s
+; RUN: verify-uselistorder %s.bc
+
+define i8* @invalid() {
+; CHECK-LABEL: define i8* @invalid() {
+; CHECK-NEXT:   %tmp0 = call i8* @foo(){{$}}
+; CHECK-NEXT:   ret i8* %tmp0
+  %tmp0 = call i8* @foo() [ "clang.arc.attachedcall"() ]
+  ret i8* %tmp0
+}
+
+define i8* @valid() {
+; CHECK-LABEL: define i8* @valid() {
+; CHECK-NEXT:   %tmp0 = call i8* @foo() [ "clang.arc.attachedcall"(i8* (i8*)* @llvm.objc.retainAutoreleasedReturnValue) ]
+; CHECK-NEXT:   ret i8* %tmp0
+  %tmp0 = call i8* @foo() [ "clang.arc.attachedcall"(i8* (i8*)* @llvm.objc.retainAutoreleasedReturnValue) ]
+  ret i8* %tmp0
+}
+
+declare i8* @foo()
+declare i8* @llvm.objc.retainAutoreleasedReturnValue(i8*)
diff --git a/llvm/test/Bitcode/upgrade-arc-attachedcall-bundle.ll.bc b/llvm/test/Bitcode/upgrade-arc-attachedcall-bundle.ll.bc
new file mode 100644
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
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