Index: include/clang/AST/Type.h
===================================================================
--- include/clang/AST/Type.h
+++ include/clang/AST/Type.h
@@ -1080,6 +1080,9 @@
   /// Strip Objective-C "__kindof" types from the given type.
   QualType stripObjCKindOfType(const ASTContext &ctx) const;
 
+  /// Strip typedefs and atomic from the given type.
+  QualType getDesugaredAtomicValueType(const ASTContext &ctx) const;
+
 private:
   // These methods are implemented in a separate translation unit;
   // "static"-ize them to avoid creating temporary QualTypes in the
Index: lib/AST/Type.cpp
===================================================================
--- lib/AST/Type.cpp
+++ lib/AST/Type.cpp
@@ -1274,6 +1274,13 @@
            });
 }
 
+QualType QualType::getDesugaredAtomicValueType(const ASTContext &Ctx) const {
+  auto *TP = getDesugaredType(Ctx).getTypePtrOrNull();
+  if (auto *AT = dyn_cast_or_null<AtomicType>(TP))
+    return AT->getValueType();
+  return *this;
+}
+
 Optional<ArrayRef<QualType>> Type::getObjCSubstitutions(
                                const DeclContext *dc) const {
   // Look through method scopes.
Index: lib/CodeGen/CGObjC.cpp
===================================================================
--- lib/CodeGen/CGObjC.cpp
+++ lib/CodeGen/CGObjC.cpp
@@ -897,9 +897,8 @@
 
     // Currently, all atomic accesses have to be through integer
     // types, so there's no point in trying to pick a prettier type.
-    llvm::Type *bitcastType =
-      llvm::Type::getIntNTy(getLLVMContext(),
-                            getContext().toBits(strategy.getIvarSize()));
+    uint64_t IVarSize = getContext().toBits(strategy.getIvarSize());
+    llvm::Type *bitcastType = llvm::Type::getIntNTy(getLLVMContext(), IVarSize);
     bitcastType = bitcastType->getPointerTo(); // addrspace 0 okay
 
     // Perform an atomic load.  This does not impose ordering constraints.
@@ -911,7 +910,16 @@
     // Store that value into the return address.  Doing this with a
     // bitcast is likely to produce some pretty ugly IR, but it's not
     // the *most* terrible thing in the world.
-    Builder.CreateStore(load, Builder.CreateBitCast(ReturnValue, bitcastType));
+    llvm::Type *RetTy = ConvertType(getterMethod->getReturnType());
+    uint64_t RetTySize = CGM.getDataLayout().getTypeSizeInBits(RetTy);
+    llvm::Value *IVarVal = load;
+    if (IVarSize > RetTySize) {
+      llvm::Type *NewTy = llvm::Type::getIntNTy(getLLVMContext(), RetTySize);
+      IVarVal = Builder.CreateTrunc(load, NewTy);
+      bitcastType = NewTy->getPointerTo();
+    }
+    Builder.CreateStore(IVarVal,
+                        Builder.CreateBitCast(ReturnValue, bitcastType));
 
     // Make sure we don't do an autorelease.
     AutoreleaseResult = false;
@@ -1010,7 +1018,9 @@
           AutoreleaseResult = false;
         }
 
-        value = Builder.CreateBitCast(value, ConvertType(propType));
+        value = Builder.CreateBitCast(
+            value,
+            ConvertType(propType.getDesugaredAtomicValueType(getContext())));
         value = Builder.CreateBitCast(
             value, ConvertType(GetterMethodDecl->getReturnType()));
       }
Index: lib/Sema/SemaDeclObjC.cpp
===================================================================
--- lib/Sema/SemaDeclObjC.cpp
+++ lib/Sema/SemaDeclObjC.cpp
@@ -4315,8 +4315,9 @@
   }
 
   ObjCMethodDecl *ObjCMethod = ObjCMethodDecl::Create(
-      Context, MethodLoc, EndLoc, Sel, resultDeclType, ReturnTInfo, CurContext,
-      MethodType == tok::minus, isVariadic,
+      Context, MethodLoc, EndLoc, Sel,
+      resultDeclType.getDesugaredAtomicValueType(Context),
+      ReturnTInfo, CurContext, MethodType == tok::minus, isVariadic,
       /*isPropertyAccessor=*/false,
       /*isImplicitlyDeclared=*/false, /*isDefined=*/false,
       MethodDeclKind == tok::objc_optional ? ObjCMethodDecl::Optional
@@ -4355,9 +4356,9 @@
       ? DI->getTypeLoc().getBeginLoc()
       : ArgInfo[i].NameLoc;
 
-    ParmVarDecl* Param = CheckParameter(ObjCMethod, StartLoc,
-                                        ArgInfo[i].NameLoc, ArgInfo[i].Name,
-                                        ArgType, DI, SC_None);
+    ParmVarDecl* Param = CheckParameter(
+        ObjCMethod, StartLoc, ArgInfo[i].NameLoc, ArgInfo[i].Name,
+        ArgType.getDesugaredAtomicValueType(Context), DI, SC_None);
 
     Param->setObjCMethodScopeInfo(i);
 
Index: lib/Sema/SemaObjCProperty.cpp
===================================================================
--- lib/Sema/SemaObjCProperty.cpp
+++ lib/Sema/SemaObjCProperty.cpp
@@ -1494,6 +1494,7 @@
     return false;
   QualType GetterType = GetterMethod->getReturnType().getNonReferenceType();
   QualType PropertyIvarType = property->getType().getNonReferenceType();
+  PropertyIvarType = PropertyIvarType.getDesugaredAtomicValueType(Context);
   bool compat = Context.hasSameType(PropertyIvarType, GetterType);
   if (!compat) {
     const ObjCObjectPointerType *propertyObjCPtr = nullptr;
@@ -2205,7 +2206,8 @@
     SourceLocation Loc = property->getLocation();
 
     // If the property is null_resettable, the getter returns nonnull.
-    QualType resultTy = property->getType();
+    QualType resultTy =
+        property->getType().getDesugaredAtomicValueType(Context);
     if (property->getPropertyAttributes() &
         ObjCPropertyDecl::OBJC_PR_null_resettable) {
       QualType modifiedTy = resultTy;
@@ -2277,6 +2279,7 @@
       // If the property is null_resettable, the setter accepts a
       // nullable value.
       QualType paramTy = property->getType().getUnqualifiedType();
+      paramTy = paramTy.getDesugaredAtomicValueType(Context);
       if (property->getPropertyAttributes() &
           ObjCPropertyDecl::OBJC_PR_null_resettable) {
         QualType modifiedTy = paramTy;
Index: test/CodeGenObjC/property-atomic-bool.m
===================================================================
--- /dev/null
+++ test/CodeGenObjC/property-atomic-bool.m
@@ -0,0 +1,34 @@
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10 -emit-llvm -x objective-c %s -o - | FileCheck %s
+
+// CHECK: define internal zeroext i1 @"\01-[A0 p]"(
+// CHECK:   %[[ATOMIC_LOAD:.*]] = load atomic i8, i8* %{{.*}} seq_cst
+// CHECK:   %[[TOBOOL:.*]] = trunc i8 %[[ATOMIC_LOAD]] to i1
+// CHECK:   ret i1 %[[TOBOOL]]
+
+// CHECK: define internal void @"\01-[A0 setP:]"({{.*}} i1 zeroext {{.*}})
+// CHECK:   store atomic i8 %{{.*}}, i8* %{{.*}} seq_cst
+// CHECK:   ret void
+
+// CHECK: define internal zeroext i1 @"\01-[A1 p]"(
+// CHECK:   %[[ATOMIC_LOAD:.*]] = load atomic i8, i8* %{{.*}} unordered
+// CHECK:   %[[TOBOOL:.*]] = trunc i8 %load to i1
+// CHECK:   ret i1 %[[TOBOOL]]
+
+// CHECK: define internal void @"\01-[A1 setP:]"({{.*}} i1 zeroext %p)
+// CHECK:   store atomic i8 %{{.*}}, i8* %{{.*}} unordered
+// CHECK:   ret void
+
+@interface A0
+@property(nonatomic) _Atomic(_Bool) p;
+@end
+@implementation A0
+@end
+
+@interface A1 {
+  _Atomic(_Bool) p;
+}
+@property _Atomic(_Bool) p;
+@end
+@implementation A1
+@synthesize p;
+@end
Index: test/SemaObjC/property-atomic-bool.m
===================================================================
--- /dev/null
+++ test/SemaObjC/property-atomic-bool.m
@@ -0,0 +1,61 @@
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.10 -ast-dump "%s" 2>&1 | FileCheck %s
+
+// CHECK: TypedefDecl {{.*}} referenced AtomicBool '_Atomic(_Bool)'
+// CHECK:  AtomicType {{.*}} '_Atomic(_Bool)'
+// CHECK:   BuiltinType {{.*}} '_Bool'
+// CHECK: ObjCInterfaceDecl {{.*}} A0
+// CHECK:  ObjCPropertyDecl {{.*}} p '_Atomic(_Bool)' {{.*}} nonatomic
+// CHECK:  ObjCMethodDecl {{.*}} implicit - p '_Bool'
+// CHECK:  ObjCMethodDecl {{.*}} implicit - setP: 'void'
+// CHECK:   ParmVarDecl {{.*}} p '_Bool'
+// CHECK: ObjCInterfaceDecl {{.*}} A1
+// CHECK:  ObjCPropertyDecl {{.*}} p 'AtomicBool':'_Atomic(_Bool)' {{.*}} nonatomic
+// CHECK:  ObjCMethodDecl {{.*}} implicit - p '_Bool'
+// CHECK:  ObjCMethodDecl {{.*}} implicit - setP: 'void'
+// CHECK:   ParmVarDecl {{.*}} p '_Bool'
+// CHECK: ObjCInterfaceDecl {{.*}} A2
+// CHECK:  ObjCIvarDecl {{.*}} p '_Atomic(_Bool)' protected
+// CHECK:  ObjCPropertyDecl {{.*}} p '_Atomic(_Bool)'
+// CHECK:  ObjCMethodDecl {{.*}} implicit - p '_Bool'
+// CHECK:  ObjCMethodDecl {{.*}} implicit - setP: 'void'
+// CHECK:   ParmVarDecl {{.*}} p '_Bool'
+// CHECK: ObjCInterfaceDecl {{.*}} A3
+// CHECK:  ObjCIvarDecl {{.*}} p 'AtomicBool':'_Atomic(_Bool)' protected
+// CHECK:  ObjCPropertyDecl {{.*}} p 'AtomicBool':'_Atomic(_Bool)'
+// CHECK:  ObjCMethodDecl {{.*}} implicit - p '_Bool'
+// CHECK:  ObjCMethodDecl {{.*}} implicit - setP: 'void'
+// CHECK:   ParmVarDecl {{.*}} p '_Bool'
+
+typedef _Atomic(_Bool) AtomicBool;
+
+@interface A0
+@property(nonatomic) _Atomic(_Bool) p;
+@end
+@implementation A0
+@end
+
+@interface A1
+@property(nonatomic) AtomicBool p;
+@end
+@implementation A1
+@end
+
+@interface A2 {
+  _Atomic(_Bool) p;
+}
+@property _Atomic(_Bool) p;
+@end
+
+@implementation A2
+@synthesize p;
+@end
+
+@interface A3 {
+  AtomicBool p;
+}
+@property AtomicBool p;
+@end
+
+@implementation A3
+@synthesize p;
+@end