Index: include/clang/Sema/Initialization.h
===================================================================
--- include/clang/Sema/Initialization.h
+++ include/clang/Sema/Initialization.h
@@ -118,6 +118,10 @@
     /// \brief Whether the entity being initialized may end up using the
     /// named return value optimization (NRVO).
     bool NRVO;
+
+    /// \brief When Kind == EK_BlockElement, this flag determines if the entity
+    /// is a lambda that's captured by a block it's converted to.
+    bool IsLambdaToBlockConversionEntity;
   };
 
   struct VD {
@@ -180,11 +184,11 @@
   /// function, throwing an object, performing an explicit cast, or
   /// initializing a parameter for which there is no declaration.
   InitializedEntity(EntityKind Kind, SourceLocation Loc, QualType Type,
-                    bool NRVO = false)
-    : Kind(Kind), Parent(nullptr), Type(Type), ManglingNumber(0)
-  {
+                    bool NRVO = false, bool IsLambdaToBlockConversion = false)
+      : Kind(Kind), Parent(nullptr), Type(Type), ManglingNumber(0) {
     LocAndNRVO.Location = Loc.getRawEncoding();
     LocAndNRVO.NRVO = NRVO;
+    LocAndNRVO.IsLambdaToBlockConversionEntity = IsLambdaToBlockConversion;
   }
   
   /// \brief Create the initialization entity for a member subobject.
@@ -256,9 +260,11 @@
     return InitializedEntity(EK_Result, ReturnLoc, Type, NRVO);
   }
 
-  static InitializedEntity InitializeBlock(SourceLocation BlockVarLoc,
-                                           QualType Type, bool NRVO) {
-    return InitializedEntity(EK_BlockElement, BlockVarLoc, Type, NRVO);
+  static InitializedEntity
+  InitializeBlock(SourceLocation BlockVarLoc, QualType Type, bool NRVO,
+                  bool IsLambdaToBlockConversion = false) {
+    return InitializedEntity(EK_BlockElement, BlockVarLoc, Type, NRVO,
+                             IsLambdaToBlockConversion);
   }
   
   /// \brief Create the initialization entity for an exception object.
@@ -388,6 +394,10 @@
   /// value optimization, which also applies to thrown objects.
   bool allowsNRVO() const;
 
+  /// \brief Determines whether this initialization is the lambda to block
+  /// entity conversion.
+  bool isLambdaToBlockEntity() const;
+
   bool isParameterKind() const {
     return (getKind() == EK_Parameter  ||
             getKind() == EK_Parameter_CF_Audited);
Index: lib/Sema/SemaInit.cpp
===================================================================
--- lib/Sema/SemaInit.cpp
+++ lib/Sema/SemaInit.cpp
@@ -3000,6 +3000,10 @@
   return false;
 }
 
+bool InitializedEntity::isLambdaToBlockEntity() const {
+  return Kind == EK_BlockElement && LocAndNRVO.IsLambdaToBlockConversionEntity;
+}
+
 unsigned InitializedEntity::dumpImpl(raw_ostream &OS) const {
   assert(getParent() != this);
   unsigned Depth = getParent() ? getParent()->dumpImpl(OS) : 0;
@@ -3625,7 +3629,8 @@
   if (S.getLangOpts().CPlusPlus1z &&
       Entity.getKind() != InitializedEntity::EK_Base &&
       Entity.getKind() != InitializedEntity::EK_Delegating &&
-      UnwrappedArgs.size() == 1 && UnwrappedArgs[0]->isRValue() &&
+      !Entity.isLambdaToBlockEntity() && UnwrappedArgs.size() == 1 &&
+      UnwrappedArgs[0]->isRValue() &&
       S.Context.hasSameUnqualifiedType(UnwrappedArgs[0]->getType(), DestType)) {
     // Convert qualifications if necessary.
     Sequence.AddQualificationConversionStep(DestType, VK_RValue);
Index: lib/Sema/SemaLambda.cpp
===================================================================
--- lib/Sema/SemaLambda.cpp
+++ lib/Sema/SemaLambda.cpp
@@ -1649,10 +1649,10 @@
   CallOperator->markUsed(Context);
 
   ExprResult Init = PerformCopyInitialization(
-                      InitializedEntity::InitializeBlock(ConvLocation, 
-                                                         Src->getType(), 
-                                                         /*NRVO=*/false),
-                      CurrentLocation, Src);
+      InitializedEntity::InitializeBlock(ConvLocation, Src->getType(),
+                                         /*NRVO=*/false,
+                                         /*IsLambdaToBlockConversion=*/true),
+      CurrentLocation, Src);
   if (!Init.isInvalid())
     Init = ActOnFinishFullExpr(Init.get());
   
Index: test/CodeGenObjCXX/lambda-to-block.mm
===================================================================
--- /dev/null
+++ test/CodeGenObjCXX/lambda-to-block.mm
@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -x objective-c++ -fblocks -triple x86_64-apple-darwin10 -fobjc-runtime=macosx-fragile-10.5 -std=c++1z -emit-llvm -o - %s | FileCheck %s
+
+// rdar://31385153
+// Shouldn't crash!
+
+void takesBlock(void (^)(void));
+
+struct Copyable {
+  Copyable(const Copyable &x);
+};
+
+void hasLambda(Copyable x) {
+  takesBlock([x] () { });
+}
+// CHECK-LABEL: __copy_helper_block_
+// CHECK: call void @_ZN8CopyableC1ERKS_
+// CHECK-LABE: __destroy_helper_block_