Index: lib/Sema/SemaLambda.cpp
===================================================================
--- lib/Sema/SemaLambda.cpp	(revision 217960)
+++ lib/Sema/SemaLambda.cpp	(working copy)
@@ -1572,14 +1572,20 @@
   CallOperator->setReferenced();
   CallOperator->markUsed(Context);
 
-  ExprResult Init = PerformCopyInitialization(
-                      InitializedEntity::InitializeBlock(ConvLocation, 
-                                                         Src->getType(), 
-                                                         /*NRVO=*/false),
-                      CurrentLocation, Src);
-  if (!Init.isInvalid())
-    Init = ActOnFinishFullExpr(Init.get());
+  ExprResult Init;
+  {
+    EnterExpressionEvaluationContext evalContext(*this, Sema::PotentiallyEvaluated);
+    ExprNeedsCleanups = !Lambda->hasTrivialDestructor();
   
+    Init = PerformCopyInitialization(
+             InitializedEntity::InitializeBlock(ConvLocation,
+                                                Src->getType(),
+                                                /*NRVO=*/false),
+                                     CurrentLocation, Src);
+    if (!Init.isInvalid())
+      Init = ActOnFinishFullExpr(Init.get());
+  }
+  
   if (Init.isInvalid())
     return ExprError();
   
Index: test/CodeGenObjCXX/lambda-in-objc-literals.mm
===================================================================
--- test/CodeGenObjCXX/lambda-in-objc-literals.mm	(revision 0)
+++ test/CodeGenObjCXX/lambda-in-objc-literals.mm	(working copy)
@@ -0,0 +1,52 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10.0.0 -emit-llvm -o - %s -fexceptions -std=c++11 -fblocks
+// rdar://16879958
+
+@protocol NSCopying @end
+typedef unsigned long NSUInteger;
+typedef long NSInteger;
+
+@interface NSDictionary
++ (id)dictionaryWithObjects:(const id [])objects forKeys:(const id <NSCopying> [])keys count:(NSUInteger)cnt;
+- (void)setObject:(id)object forKeyedSubscript:(id)key;
+- (id)objectForKeyedSubscript:(id)key;
++ (id) alloc;
+- (id)initWithObjects:(const id [])objects forKeys:(const id [])keys count:(unsigned long)cnt;
+@end
+
+@interface NSString<NSCopying>
+@end
+
+
+@class NSFastEnumerationState;
+
+@protocol NSFastEnumeration
+
+- (NSUInteger)countByEnumeratingWithState:(NSFastEnumerationState *)state objects:(id [])buffer count:(NSUInteger)len;
+
+@end
+
+@interface NSNumber
++ (NSNumber *)numberWithInt:(int)value;
+@end
+
+@interface NSArray <NSFastEnumeration>
++ (id) alloc;
++ (id)arrayWithObjects:(const id [])objects count:(NSUInteger)cnt;
+@end
+
+id test_dict()
+{
+        return @{
+                @"a": [](){},
+                @"b": [](){},
+                @"c": [](){}
+        };
+}
+
+id test_arr()
+{
+        return @[
+                [](){},
+                [](){}
+        ];
+}