diff --git a/include/clang/APINotes/Types.h b/include/clang/APINotes/Types.h
index fae5501..09fbc8d 100644
--- a/include/clang/APINotes/Types.h
+++ b/include/clang/APINotes/Types.h
@@ -336,8 +336,13 @@
 
 /// Describes API notes data for an Objective-C property.
 class ObjCPropertyInfo : public VariableInfo {
+  unsigned SwiftImportAsAccessorsSpecified : 1;
+  unsigned SwiftImportAsAccessors : 1;
+
 public:
-  ObjCPropertyInfo() : VariableInfo() { }
+  ObjCPropertyInfo()
+      : VariableInfo(), SwiftImportAsAccessorsSpecified(false),
+        SwiftImportAsAccessors(false) {}
 
   /// Merge class-wide information into the given property.
   friend ObjCPropertyInfo &operator|=(ObjCPropertyInfo &lhs,
@@ -351,6 +356,32 @@
 
     return lhs;
   }
+
+  Optional<bool> getSwiftImportAsAccessors() const {
+    if (SwiftImportAsAccessorsSpecified)
+      return SwiftImportAsAccessors;
+    return None;
+  }
+  void setSwiftImportAsAccessors(Optional<bool> value) {
+    if (value.hasValue()) {
+      SwiftImportAsAccessorsSpecified = true;
+      SwiftImportAsAccessors = value.getValue();
+    } else {
+      SwiftImportAsAccessorsSpecified = false;
+      SwiftImportAsAccessors = false;
+    }
+  }
+
+  friend ObjCPropertyInfo &operator|=(ObjCPropertyInfo &lhs,
+                                      const ObjCPropertyInfo &rhs) {
+    lhs |= static_cast<const VariableInfo &>(rhs);
+    if (!lhs.SwiftImportAsAccessorsSpecified &&
+        rhs.SwiftImportAsAccessorsSpecified) {
+      lhs.SwiftImportAsAccessorsSpecified = true;
+      lhs.SwiftImportAsAccessors = rhs.SwiftImportAsAccessors;
+    }
+    return lhs;
+  }
 };
 
 /// Describes a function or method parameter.
diff --git a/include/clang/Basic/Attr.td b/include/clang/Basic/Attr.td
index e12450b..18efa4b 100644
--- a/include/clang/Basic/Attr.td
+++ b/include/clang/Basic/Attr.td
@@ -1449,6 +1449,14 @@
   let Documentation = [Undocumented];
 }
 
+def SwiftImportPropertyAsAccessors : InheritableAttr { 
+  // This attribute has no spellings as it is only ever created implicitly
+  // from API notes.
+  let Spellings = [];
+  let SemaHandler = 0;
+  let Documentation = [Undocumented];
+}
+
 def ReqdWorkGroupSize : InheritableAttr {
   let Spellings = [GNU<"reqd_work_group_size">];
   let Args = [UnsignedArgument<"XDim">, UnsignedArgument<"YDim">,
diff --git a/lib/APINotes/APINotesFormat.h b/lib/APINotes/APINotesFormat.h
index 4623773..b3d2d36 100644
--- a/lib/APINotes/APINotesFormat.h
+++ b/lib/APINotes/APINotesFormat.h
@@ -36,7 +36,7 @@
 /// API notes file minor version number.
 ///
 /// When the format changes IN ANY WAY, this number should be incremented.
-const uint16_t VERSION_MINOR = 19;  // SwiftWrapper
+const uint16_t VERSION_MINOR = 20;  // ImportPropertyAsAccessors
 
 using IdentifierID = PointerEmbeddedInt<unsigned, 31>;
 using IdentifierIDField = BCVBR<16>;
diff --git a/lib/APINotes/APINotesReader.cpp b/lib/APINotes/APINotesReader.cpp
index 9dee73c..1daf27b 100644
--- a/lib/APINotes/APINotesReader.cpp
+++ b/lib/APINotes/APINotesReader.cpp
@@ -285,6 +285,9 @@
                                             const uint8_t *&data) {
       ObjCPropertyInfo info;
       readVariableInfo(data, info);
+      uint8_t flags = *data++;
+      if (flags & (1 << 0))
+        info.setSwiftImportAsAccessors(flags & (1 << 1));
       return info;
     }
   };
diff --git a/lib/APINotes/APINotesWriter.cpp b/lib/APINotes/APINotesWriter.cpp
index c0527aa..d696aa6 100644
--- a/lib/APINotes/APINotesWriter.cpp
+++ b/lib/APINotes/APINotesWriter.cpp
@@ -606,11 +606,17 @@
     }
 
     unsigned getUnversionedInfoSize(const ObjCPropertyInfo &info) {
-      return getVariableInfoSize(info);
+      return getVariableInfoSize(info) + 1;
     }
 
     void emitUnversionedInfo(raw_ostream &out, const ObjCPropertyInfo &info) {
       emitVariableInfo(out, info);
+      uint8_t flags = 0;
+      if (Optional<bool> value = info.getSwiftImportAsAccessors()) {
+        flags |= 1 << 0;
+        flags |= value.getValue() << 1;
+      }
+      out << flags;
     }
   };
 } // end anonymous namespace
diff --git a/lib/APINotes/APINotesYAMLCompiler.cpp b/lib/APINotes/APINotesYAMLCompiler.cpp
index d24a63f..1f3783c 100644
--- a/lib/APINotes/APINotesYAMLCompiler.cpp
+++ b/lib/APINotes/APINotesYAMLCompiler.cpp
@@ -199,6 +199,7 @@
     AvailabilityItem Availability;
     Optional<bool> SwiftPrivate;
     StringRef SwiftName;
+    Optional<bool> SwiftImportAsAccessors;
   };
   typedef std::vector<Property> PropertiesSeq;
 
@@ -398,6 +399,7 @@
         io.mapOptional("AvailabilityMsg", p.Availability.Msg);
         io.mapOptional("SwiftPrivate",    p.SwiftPrivate);
         io.mapOptional("SwiftName",       p.SwiftName);
+        io.mapOptional("SwiftImportAsAccessors", p.SwiftImportAsAccessors);
       }
     };
 
@@ -784,6 +786,8 @@
         pInfo.SwiftName = prop.SwiftName;
         if (prop.Nullability)
           pInfo.setNullabilityAudited(*prop.Nullability);
+        if (prop.SwiftImportAsAccessors)
+          pInfo.setSwiftImportAsAccessors(*prop.SwiftImportAsAccessors);
         if (prop.Kind) {
           Writer->addObjCProperty(clID, prop.Name,
                                   *prop.Kind == MethodKind::Instance, pInfo,
@@ -1197,6 +1201,8 @@
         property.Nullability = *nullability;
       }
 
+      property.SwiftImportAsAccessors = info.getSwiftImportAsAccessors();
+
       auto &items = getTopLevelItems(swiftVersion);
       knownContexts[contextID.Value].getContext(swiftVersion, items)
         .Properties.push_back(property);
diff --git a/lib/Sema/SemaAPINotes.cpp b/lib/Sema/SemaAPINotes.cpp
index 121a730..8f09313 100644
--- a/lib/Sema/SemaAPINotes.cpp
+++ b/lib/Sema/SemaAPINotes.cpp
@@ -310,6 +310,13 @@
   // Handle common entity information.
   ProcessAPINotes(S, D, static_cast<const api_notes::VariableInfo &>(info),
                   role);
+  if (auto asAccessors = info.getSwiftImportAsAccessors()) {
+    handleAPINotedAttribute<SwiftImportPropertyAsAccessorsAttr>(S, D,
+                                                                *asAccessors,
+                                                                role, [&] {
+      return SwiftImportPropertyAsAccessorsAttr::CreateImplicit(S.Context);
+    });
+  }
 }
 
 namespace {
diff --git a/test/APINotes/Inputs/Frameworks/VersionedKit.framework/Headers/VersionedKit.apinotes b/test/APINotes/Inputs/Frameworks/VersionedKit.framework/Headers/VersionedKit.apinotes
index 4215fb9..c3b70b6 100644
--- a/test/APINotes/Inputs/Frameworks/VersionedKit.framework/Headers/VersionedKit.apinotes
+++ b/test/APINotes/Inputs/Frameworks/VersionedKit.framework/Headers/VersionedKit.apinotes
@@ -1,9 +1,38 @@
-Name: SomeKit
+Name: VersionedKit
+Classes:
+  - Name: TestProperties
+    Properties:
+      - Name: accessorsOnly
+        PropertyKind:    Instance
+        SwiftImportAsAccessors: true
+      - Name: accessorsOnlyForClass
+        PropertyKind:    Class
+        SwiftImportAsAccessors: true
+      - Name: accessorsOnlyExceptInVersion3
+        PropertyKind:    Instance
+        SwiftImportAsAccessors: true
+      - Name: accessorsOnlyForClassExceptInVersion3
+        PropertyKind:    Class
+        SwiftImportAsAccessors: true
 SwiftVersions:
   - Version: 3.0
     Classes:
       - Name: MyReferenceType
         SwiftBridge: ''
+      - Name: TestProperties
+        Properties:
+          - Name: accessorsOnlyInVersion3
+            PropertyKind:    Instance
+            SwiftImportAsAccessors: true
+          - Name: accessorsOnlyForClassInVersion3
+            PropertyKind:    Class
+            SwiftImportAsAccessors: true
+          - Name: accessorsOnlyExceptInVersion3
+            PropertyKind:    Instance
+            SwiftImportAsAccessors: false
+          - Name: accessorsOnlyForClassExceptInVersion3
+            PropertyKind:    Class
+            SwiftImportAsAccessors: false
     Functions:
       - Name: moveToPoint
         SwiftName: 'moveTo(a:b:)'
diff --git a/test/APINotes/Inputs/Frameworks/VersionedKit.framework/Headers/VersionedKit.h b/test/APINotes/Inputs/Frameworks/VersionedKit.framework/Headers/VersionedKit.h
index db71d8f..ffbc7df 100644
--- a/test/APINotes/Inputs/Frameworks/VersionedKit.framework/Headers/VersionedKit.h
+++ b/test/APINotes/Inputs/Frameworks/VersionedKit.framework/Headers/VersionedKit.h
@@ -17,3 +17,14 @@
 void privateFunc(void) __attribute__((swift_private));
 
 typedef double MyDoubleWrapper __attribute__((swift_wrapper(struct)));
+
+@interface TestProperties
+@property (nonatomic, readwrite, retain) id accessorsOnly;
+@property (nonatomic, readwrite, retain, class) id accessorsOnlyForClass;
+
+@property (nonatomic, readwrite, retain) id accessorsOnlyInVersion3;
+@property (nonatomic, readwrite, retain, class) id accessorsOnlyForClassInVersion3;
+
+@property (nonatomic, readwrite, retain) id accessorsOnlyExceptInVersion3;
+@property (nonatomic, readwrite, retain, class) id accessorsOnlyForClassExceptInVersion3;
+@end
diff --git a/test/APINotes/Inputs/roundtrip.apinotes b/test/APINotes/Inputs/roundtrip.apinotes
index c6beaf19..68169c4 100644
--- a/test/APINotes/Inputs/roundtrip.apinotes
+++ b/test/APINotes/Inputs/roundtrip.apinotes
@@ -104,6 +104,7 @@
         AvailabilityMsg: ''
         SwiftPrivate:    false
         SwiftName:       ''
+        SwiftImportAsAccessors: false
 Functions:       
   - Name:            NSAvailableWindowDepths
     NullabilityOfRet: N
@@ -162,3 +163,14 @@
             SwiftPrivate:    true
             SwiftName:       ''
             DesignatedInit:  true
+      - Name:            NSView
+        Availability:    available
+        AvailabilityMsg: ''
+        SwiftName:       ''
+        Properties:      
+          - Name:            makeBackingLayer
+            PropertyKind:    Class
+            Availability:    available
+            AvailabilityMsg: ''
+            SwiftName:       ''
+            SwiftImportAsAccessors: true
diff --git a/test/APINotes/properties.m b/test/APINotes/properties.m
new file mode 100644
index 0000000..a4c925b
--- /dev/null
+++ b/test/APINotes/properties.m
@@ -0,0 +1,31 @@
+// RUN: rm -rf %t && mkdir -p %t
+
+// RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t/ModulesCache -fapinotes-modules -fapinotes-cache-path=%t/APINotesCache -fblocks -fsyntax-only -I %S/Inputs/Headers -F %S/Inputs/Frameworks %s -ast-dump -ast-dump-filter 'TestProperties::' | FileCheck -check-prefix=CHECK -check-prefix=CHECK-4 %s
+// RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t/ModulesCache -fapinotes-modules -fapinotes-cache-path=%t/APINotesCache -fblocks -fsyntax-only -I %S/Inputs/Headers -F %S/Inputs/Frameworks %s -ast-dump -ast-dump-filter 'TestProperties::' -fapinotes-swift-version=3 | FileCheck -check-prefix=CHECK -check-prefix=CHECK-3 %s
+
+// I know, FileChecking an AST dump is brittle. However, the attributes being
+// tested aren't used for anything by Clang, and don't even have a spelling.
+
+@import VersionedKit;
+
+// CHECK-LABEL: ObjCPropertyDecl {{.+}} accessorsOnly 'id'
+// CHECK-NEXT: SwiftImportPropertyAsAccessorsAttr {{.+}} Implicit
+
+// CHECK-LABEL: ObjCPropertyDecl {{.+}} accessorsOnlyForClass 'id'
+// CHECK-NEXT: SwiftImportPropertyAsAccessorsAttr {{.+}} Implicit
+
+// CHECK-LABEL: ObjCPropertyDecl {{.+}} accessorsOnlyInVersion3 'id'
+// CHECK-3-NEXT: SwiftImportPropertyAsAccessorsAttr {{.+}} Implicit
+// CHECK-4-NEXT: {{^$}}
+
+// CHECK-LABEL: ObjCPropertyDecl {{.+}} accessorsOnlyForClassInVersion3 'id'
+// CHECK-3-NEXT: SwiftImportPropertyAsAccessorsAttr {{.+}} Implicit
+// CHECK-4-NEXT: {{^$}}
+
+// CHECK-LABEL: ObjCPropertyDecl {{.+}} accessorsOnlyExceptInVersion3 'id'
+// CHECK-3-NEXT: {{^$}}
+// CHECK-4-NEXT: SwiftImportPropertyAsAccessorsAttr {{.+}} Implicit
+
+// CHECK-LABEL: ObjCPropertyDecl {{.+}} accessorsOnlyForClassExceptInVersion3 'id'
+// CHECK-3-NEXT: {{^$}}
+// CHECK-4-NEXT: SwiftImportPropertyAsAccessorsAttr {{.+}} Implicit