diff --git a/lib/AST/GenericSignatureBuilder.cpp b/lib/AST/GenericSignatureBuilder.cpp
index 89a9baf..8b69e36 100644
--- a/lib/AST/GenericSignatureBuilder.cpp
+++ b/lib/AST/GenericSignatureBuilder.cpp
@@ -1775,7 +1775,7 @@
 bool FloatingRequirementSource::isRecursive(
                                     Type rootType,
                                     GenericSignatureBuilder &builder) const {
-  llvm::SmallSet<std::pair<CanType, ProtocolDecl *>, 4> visitedAssocReqs;
+  llvm::SmallSet<std::pair<CanType, ProtocolDecl *>, 32> visitedAssocReqs;
   for (auto storedSource = storage.dyn_cast<const RequirementSource *>();
        storedSource; storedSource = storedSource->parent) {
     // FIXME: isRecursive() is completely misnamed
diff --git a/lib/Basic/Statistic.cpp b/lib/Basic/Statistic.cpp
index 35fceb3..78bcdeb 100644
--- a/lib/Basic/Statistic.cpp
+++ b/lib/Basic/Statistic.cpp
@@ -621,7 +621,7 @@
   raw_fd_ostream ostream(StatsFilename, EC, fs::F_Append | fs::F_Text);
   if (EC) {
     llvm::errs() << "Error opening -stats-output-dir file '"
-                 << TraceFilename << "' for writing\n";
+                 << StatsFilename << "' for writing\n";
     return;
   }
 
diff --git a/lib/SIL/DynamicCasts.cpp b/lib/SIL/DynamicCasts.cpp
index c5551b1..56c6c6c 100644
--- a/lib/SIL/DynamicCasts.cpp
+++ b/lib/SIL/DynamicCasts.cpp
@@ -1134,19 +1134,22 @@
     if (!objectType.isAnyClassReferenceType())
       return false;
     
+    if (M.getASTContext().LangOpts.EnableObjCInterop) {
       auto super = archetype->getSuperclass();
       if (super.isNull())
         return false;
 
-    // A base class constraint that isn't NSError rules out the archetype being
-    // bound to NSError.
-    if (M.getASTContext().LangOpts.EnableObjCInterop) {
-      if (auto nserror = M.Types.getNSErrorType())
-         return !super->isEqual(nserror);
+      // A base class constraint that isn't NSError rules out the archetype being
+      // bound to NSError.
+        if (auto nserror = M.Types.getNSErrorType())
+          return !super->isEqual(nserror);
+      // If NSError wasn't loaded, any base class constraint must not be NSError.
+      return true;
+    } else {
+      // If ObjC bridging isn't enabled, we can do a scalar cast from any
+      // reference type to any class-constrained archetype.
+      return archetype->requiresClass();
     }
-    
-    // If NSError wasn't loaded, any base class constraint must not be NSError.
-    return true;
   }
   
   if (M.getASTContext().LangOpts.EnableObjCInterop
diff --git a/lib/Sema/CSApply.cpp b/lib/Sema/CSApply.cpp
index b32aa54..ca67203 100644
--- a/lib/Sema/CSApply.cpp
+++ b/lib/Sema/CSApply.cpp
@@ -3686,7 +3686,10 @@
       auto *locator = cs.getConstraintLocator(expr);
 
       if (!choice) {
-        choice = solution.getDisjunctionChoice(locator);
+        if (tc.Context.LangOpts.EnableObjCInterop)
+          choice = solution.getDisjunctionChoice(locator);
+        else
+          choice = 0;
       }
 
       // Handle the coercion/bridging of the underlying subexpression, where
diff --git a/lib/Sema/CSSimplify.cpp b/lib/Sema/CSSimplify.cpp
index 6593d89..6556fa6 100644
--- a/lib/Sema/CSSimplify.cpp
+++ b/lib/Sema/CSSimplify.cpp
@@ -3627,6 +3627,11 @@
                                              Type type2,
                                              TypeMatchOptions flags,
                                              ConstraintLocatorBuilder locator) {
+  // There's no bridging without ObjC interop, so we shouldn't have set up
+  // bridging constraints without it.
+  assert(TC.Context.LangOpts.EnableObjCInterop
+         && "bridging constraint w/o ObjC interop?!");
+  
   TypeMatchOptions subflags = getDefaultDecompositionOptions(flags);
 
   /// Form an unresolved result.
@@ -5071,11 +5076,14 @@
   coerceConstraint->setFavored();
   constraints.push_back(coerceConstraint);
 
-  // The source type can be explicitly converted to the destination type.
-  Constraint *bridgingConstraint =
-  Constraint::create(*this, ConstraintKind::BridgingConversion,
-                     fromType, toType, locatorPtr);
-  constraints.push_back(bridgingConstraint);
+  // Bridging.
+  if (getASTContext().LangOpts.EnableObjCInterop) {
+    // The source type can be explicitly converted to the destination type.
+    Constraint *bridgingConstraint =
+      Constraint::create(*this, ConstraintKind::BridgingConversion,
+                         fromType, toType, locatorPtr);
+    constraints.push_back(bridgingConstraint);
+  }
 
   if (allowFixes && shouldAttemptFixes()) {
     Constraint *downcastConstraint =
@@ -5086,8 +5094,8 @@
   }
 
   addDisjunctionConstraint(constraints, locator,
-                           allowFixes ? RememberChoice
-                                      : ForgetChoice);
+    getASTContext().LangOpts.EnableObjCInterop && allowFixes ? RememberChoice
+                                                             : ForgetChoice);
 }
 
 ConstraintSystem::SolutionKind
diff --git a/lib/Sema/Constraint.cpp b/lib/Sema/Constraint.cpp
index 622cfb1..68a7545 100644
--- a/lib/Sema/Constraint.cpp
+++ b/lib/Sema/Constraint.cpp
@@ -612,6 +612,10 @@
   assert((kind != ConstraintKind::LiteralConformsTo) ||
          second->is<ProtocolType>());
 
+  // Bridging constraints require bridging to be enabled.
+  assert(kind != ConstraintKind::BridgingConversion
+         || cs.TC.Context.LangOpts.EnableObjCInterop);
+
   // Create the constraint.
   unsigned size = totalSizeToAlloc<TypeVariableType*>(typeVars.size());
   void *mem = cs.getAllocator().Allocate(size, alignof(Constraint));
diff --git a/lib/Sema/TypeCheckConstraints.cpp b/lib/Sema/TypeCheckConstraints.cpp
index 560c2d1..0afa47c 100644
--- a/lib/Sema/TypeCheckConstraints.cpp
+++ b/lib/Sema/TypeCheckConstraints.cpp
@@ -2881,7 +2881,8 @@
 
 bool TypeChecker::isObjCBridgedTo(Type type1, Type type2, DeclContext *dc,
                                   bool *unwrappedIUO) {
-  return (typesSatisfyConstraint(type1, type2,
+  return (Context.LangOpts.EnableObjCInterop &&
+          typesSatisfyConstraint(type1, type2,
                                  /*openArchetypes=*/false,
                                  ConstraintKind::BridgingConversion,
                                  dc, unwrappedIUO));
@@ -3393,8 +3394,9 @@
   }
   
   // Check for a bridging conversion.
-  // Anything bridges to AnyObject.
-  if (toType->isAnyObject())
+  // Anything bridges to AnyObject in ObjC interop mode.
+  if (Context.LangOpts.EnableObjCInterop
+      && toType->isAnyObject())
     return CheckedCastKind::BridgingCoercion;
   
   // Do this check later in Swift 3 mode so that we check for NSNumber and
diff --git a/stdlib/public/SDK/ObjectiveC/ObjectiveC.swift b/stdlib/public/SDK/ObjectiveC/ObjectiveC.swift
index afa3931..9639638 100644
--- a/stdlib/public/SDK/ObjectiveC/ObjectiveC.swift
+++ b/stdlib/public/SDK/ObjectiveC/ObjectiveC.swift
@@ -10,8 +10,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if _runtime(_ObjC)
-
 @_exported
 import ObjectiveC
 import _SwiftObjectiveCOverlayShims
@@ -227,5 +225,3 @@
   }
 }
 
-#endif
-
diff --git a/stdlib/public/core/BridgeObjectiveC.swift b/stdlib/public/core/BridgeObjectiveC.swift
index 0bfef9a..b26c720 100644
--- a/stdlib/public/core/BridgeObjectiveC.swift
+++ b/stdlib/public/core/BridgeObjectiveC.swift
@@ -10,6 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#if _runtime(_ObjC)
 /// A Swift Array or Dictionary of types conforming to
 /// `_ObjectiveCBridgeable` can be passed to Objective-C as an NSArray or
 /// NSDictionary, respectively.  The elements of the resulting NSArray
@@ -82,8 +83,6 @@
       -> Self
 }
 
-#if _runtime(_ObjC)
-
 //===--- Bridging for metatypes -------------------------------------------===//
 
 /// A stand-in for a value of metatype type.
@@ -641,200 +640,3 @@
 }
 
 #endif
-
-//===--- Bridging without the ObjC runtime --------------------------------===//
-
-#if !_runtime(_ObjC)
-
-/// Convert `x` from its Objective-C representation to its Swift
-/// representation.
-/// COMPILER_INTRINSIC
-@_inlineable // FIXME(sil-serialize-all)
-public func _forceBridgeFromObjectiveC_bridgeable<T:_ObjectiveCBridgeable> (
-  _ x: T._ObjectiveCType,
-  _: T.Type
-) -> T {
-  var result: T?
-  T._forceBridgeFromObjectiveC(x, result: &result)
-  return result!
-}
-
-/// Attempt to convert `x` from its Objective-C representation to its Swift
-/// representation.
-/// COMPILER_INTRINSIC
-@_inlineable // FIXME(sil-serialize-all)
-public func _conditionallyBridgeFromObjectiveC_bridgeable<T:_ObjectiveCBridgeable>(
-  _ x: T._ObjectiveCType,
-  _: T.Type
-) -> T? {
-  var result: T?
-  T._conditionallyBridgeFromObjectiveC (x, result: &result)
-  return result
-}
-
-public // SPI(Foundation)
-protocol _NSSwiftValue: class {
-  init(_ value: Any)
-  var value: Any { get }
-  static var null: AnyObject { get }
-}
-
-@usableFromInline
-internal class _SwiftValue {
-  @usableFromInline
-  let value: Any
-  
-  @usableFromInline
-  init(_ value: Any) {
-    self.value = value
-  }
-  
-  @usableFromInline
-  static let null = _SwiftValue(Optional<Any>.none as Any)
-}
-
-/// COMPILER_INTRISIC
-@_silgen_name("swift_unboxFromSwiftValueWithType")
-public func swift_unboxFromSwiftValueWithType<T>(
-  _ source: inout AnyObject,
-  _ result: UnsafeMutablePointer<T>
-  ) -> Bool {
-
-  if source === _nullPlaceholder {
-    if let unpacked = Optional<Any>.none as? T {
-      result.initialize(to: unpacked)
-      return true
-    }
-  }
-    
-  if let box = source as? _SwiftValue {
-    if let value = box.value as? T {
-      result.initialize(to: value)
-      return true
-    }
-  } else if let box = source as? _NSSwiftValue {
-    if let value = box.value as? T {
-      result.initialize(to: value)
-      return true
-    }
-  }
-  
-  return false
-}
-
-@_silgen_name("_swift_extractDynamicValue")
-public func _extractDynamicValue<T>(_ value: T) -> AnyObject?
-
-@_silgen_name("_swift_bridgeToObjectiveCUsingProtocolIfPossible")
-public func _bridgeToObjectiveCUsingProtocolIfPossible<T>(_ value: T) -> AnyObject?
-
-@usableFromInline
-protocol _Unwrappable {
-  func unwrap() -> Any?
-}
-
-extension Optional: _Unwrappable {
-  func unwrap() -> Any? {
-    return self
-  }
-}
-
-// This is a best-effort tripmine for detecting the situation
-// (which should never happen) of Swift._SwiftValue and
-// Foundation._SwiftValue/Foundation.NSNull being used 
-// in the same process.
-
-@usableFromInline
-internal enum _SwiftValueFlavor: Equatable {
-  case stdlib
-  case foundation
-}
-
-@usableFromInline
-func _currentSwiftValueFlavor() -> _SwiftValueFlavor {
-  if _typeByName("Foundation._SwiftValue") as? _NSSwiftValue.Type != nil {
-    return .foundation
-  } else {
-    return .stdlib
-  }
-}
-
-@usableFromInline
-internal var _selectedSwiftValueFlavor: _SwiftValueFlavor = _currentSwiftValueFlavor()
-
-@usableFromInline
-internal func _assertSwiftValueFlavorIsConsistent() {
-  assert(_selectedSwiftValueFlavor == _currentSwiftValueFlavor())
-}
-
-@usableFromInline
-internal var _nullPlaceholder: AnyObject {
-  _assertSwiftValueFlavorIsConsistent()
-  if let foundationType = _typeByName("Foundation._SwiftValue") as? _NSSwiftValue.Type {
-    return foundationType.null
-  } else {
-    return _SwiftValue.null
-  }
-}
-
-@usableFromInline
-func _makeSwiftValue(_ value: Any) -> AnyObject {
-  _assertSwiftValueFlavorIsConsistent()
-  if let foundationType = _typeByName("Foundation._SwiftValue") as? _NSSwiftValue.Type {
-    return foundationType.init(value)
-  } else {
-    return _SwiftValue(value)
-  }
-}
-
-/// Bridge an arbitrary value to an Objective-C object.
-///
-/// - If `T` is a class type, it is always bridged verbatim, the function
-///   returns `x`;
-///
-/// - otherwise, if `T` conforms to `_ObjectiveCBridgeable`,
-///   returns the result of `x._bridgeToObjectiveC()`;
-///
-/// - otherwise, we use **boxing** to bring the value into Objective-C.
-///   The value is wrapped in an instance of a private Objective-C class
-///   that is `id`-compatible and dynamically castable back to the type of
-///   the boxed value, but is otherwise opaque.
-///
-/// COMPILER_INTRINSIC
-@inlinable // FIXME(sil-serialize-all)
-public func _bridgeAnythingToObjectiveC<T>(_ x: T) -> AnyObject {
-  var done = false
-  var result: AnyObject!
-  
-  var source: Any = x
-  
-  if let dynamicSource = _extractDynamicValue(x) {
-    result = dynamicSource as AnyObject
-    done = true 
-  }
-  
-  if !done, let wrapper = source as? _Unwrappable {
-    if let value = wrapper.unwrap() {
-      result = value as AnyObject
-    } else {
-      result = _nullPlaceholder
-    }
-    
-    done = true
-  }
-
-  if !done {
-    if type(of: source) as? AnyClass != nil {
-      result = unsafeBitCast(x, to: AnyObject.self)
-    } else if let object = _bridgeToObjectiveCUsingProtocolIfPossible(source) {
-      result = object
-    } else {
-      result = _makeSwiftValue(source)
-    }
-  }
-  
-  return result
-}
-
-#endif // !_runtime(_ObjC)
-
diff --git a/stdlib/public/core/Codable.swift.gyb b/stdlib/public/core/Codable.swift.gyb
index 926e4be..c9740c3 100644
--- a/stdlib/public/core/Codable.swift.gyb
+++ b/stdlib/public/core/Codable.swift.gyb
@@ -1171,7 +1171,7 @@
   public var _userInfo: AnyObject? {
     // The error dictionary must be returned as an AnyObject. We can do this
     // only on platforms with bridging, unfortunately.
-    #if _runtime(_ObjC)
+    #if os(macOS) || os(iOS) || os(watchOS) || os(tvOS)
       let context: Context
       switch self {
       case .invalidValue(_, let c): context = c
@@ -1281,7 +1281,7 @@
   public var _userInfo: AnyObject? {
     // The error dictionary must be returned as an AnyObject. We can do this
     // only on platforms with bridging, unfortunately.
-    #if _runtime(_ObjC)
+    #if os(macOS) || os(iOS) || os(watchOS) || os(tvOS)
       let context: Context
       switch self {
       case .keyNotFound(_,   let c): context = c
diff --git a/stdlib/public/core/SmallString.swift b/stdlib/public/core/SmallString.swift
index a8e200c..8828164 100644
--- a/stdlib/public/core/SmallString.swift
+++ b/stdlib/public/core/SmallString.swift
@@ -464,10 +464,7 @@
 
   // NOTE: This exists to facilitate _fromCodeUnits, which is awful for this use
   // case. Please don't call this from anywhere else.
-  @usableFromInline
-  @inline(never) // @outlined
-  // @_specialize(where Encoding == UTF16)
-  // @_specialize(where Encoding == UTF8)
+  @inlinable
   init?<S: Sequence, Encoding: Unicode.Encoding>(
     _fromCodeUnits codeUnits: S,
     utf16Length: Int,
diff --git a/stdlib/public/runtime/Casting.cpp b/stdlib/public/runtime/Casting.cpp
index ac711bd..26e1ad9 100644
--- a/stdlib/public/runtime/Casting.cpp
+++ b/stdlib/public/runtime/Casting.cpp
@@ -196,6 +196,7 @@
                            targetType, targetName.c_str(), message);
 }
 
+#if SWIFT_OBJC_INTEROP
 // Objective-C bridging helpers.
 namespace {
   struct _ObjectiveCBridgeableWitnessTable;
@@ -226,6 +227,7 @@
                const Metadata *targetType,
                const _ObjectiveCBridgeableWitnessTable *targetBridgeWitness,
                DynamicCastFlags flags);
+#endif
 
 /// A convenient method for failing out of a dynamic cast.
 static bool _fail(OpaqueValue *srcValue, const Metadata *srcType,
@@ -798,7 +800,7 @@
     // A fallback to use if we don't have a more specialized approach
     // for a non-class type.
     auto fallbackForNonClass = [&] {
-#if SWIFT_OBJC_INTEROP // TODO
+#if SWIFT_OBJC_INTEROP
       // If the destination type is a set of protocols that SwiftValue
       // implements, we're fine.
       if (findSwiftValueConformances(targetType,
@@ -858,6 +860,7 @@
 
     case MetadataKind::Enum:
     case MetadataKind::Optional:
+#if SWIFT_OBJC_INTEROP
       // If the source type is bridged to Objective-C, try to bridge.
       if (auto srcBridgeWitness = findBridgeWitness(srcDynamicType)) {
         bool success = _dynamicCastValueToClassExistentialViaObjCBridgeable(
@@ -870,6 +873,7 @@
         maybeDeallocateSource(success);
         return success;
       }
+#endif
       LLVM_FALLTHROUGH;
 
     case MetadataKind::Function:
@@ -1327,6 +1331,7 @@
 /********************************** Classes ***********************************/
 /******************************************************************************/
 
+#if SWIFT_OBJC_INTEROP
 /// Do a dynamic cast to the target class.
 static void *_dynamicCastUnknownClass(void *object,
                                       const Metadata *targetType,
@@ -1339,6 +1344,7 @@
 
   return const_cast<void*>(swift_dynamicCastUnknownClass(object, targetType));
 }
+#endif
 
 static bool _dynamicCastUnknownClassIndirect(OpaqueValue *dest,
                                              void *object,
@@ -2047,13 +2053,7 @@
 /**************************** Bridging _SwiftValue ****************************/
 /******************************************************************************/
 
-#if !SWIFT_OBJC_INTEROP // _SwiftValue is a native class
-SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
-bool swift_unboxFromSwiftValueWithType(OpaqueValue *source,
-                                       OpaqueValue *result,
-                                       const Metadata *destinationType);
-#endif
-
+#if SWIFT_OBJC_INTEROP
 /// Try to unbox a _SwiftValue box to perform a dynamic cast.
 static bool tryDynamicCastBoxedSwiftValue(OpaqueValue *dest,
                                           OpaqueValue *src,
@@ -2071,14 +2071,6 @@
       return false;
   }
   
-#if !SWIFT_OBJC_INTEROP // _SwiftValue is a native class:
-  // TODO: memory management?
-  if (swift_unboxFromSwiftValueWithType(src, dest, targetType)) {
-    return true;
-  }
-#endif
-  
-#if SWIFT_OBJC_INTEROP // _SwiftValue is an ObjC class:
   id srcObject;
   memcpy(&srcObject, src, sizeof(id));
   
@@ -2118,10 +2110,10 @@
       objc_release((id)srcSwiftValue);
     return true;
   }
-#endif
   
   return false;
 }
+#endif
 
 /******************************************************************************/
 /******************************** Collections *********************************/
@@ -2416,6 +2408,7 @@
   if (!srcType)
     return unwrapResult.success;
 
+#if SWIFT_OBJC_INTEROP
   // A class or AnyObject reference may point to a _SwiftValue box.
   {
     auto innerFlags = flags - DynamicCastFlags::Unconditional
@@ -2430,6 +2423,7 @@
       // (for example, casting _SwiftValue to NSObject will be successful)
     }
   }
+#endif
 
   switch (targetType->getKind()) {
   // Handle wrapping an Optional target.
@@ -2438,6 +2432,7 @@
     // unwrapping the target. This handles an optional source wrapped within an
     // existential that Optional conforms to (Any).
     if (auto srcExistentialType = dyn_cast<ExistentialTypeMetadata>(srcType)) {
+#if SWIFT_OBJC_INTEROP
       // If coming from AnyObject, we may want to bridge.
       if (isAnyObjectExistentialType(srcExistentialType)) {
         if (auto targetBridgeWitness = findBridgeWitness(targetType)) {
@@ -2447,6 +2442,7 @@
                                                            flags);
         }
       }
+#endif
       return _dynamicCastFromExistential(dest, src, srcExistentialType,
                                          targetType, flags);
     }
@@ -2511,6 +2507,7 @@
 
     case MetadataKind::Enum:
     case MetadataKind::Optional: {
+#if SWIFT_OBJC_INTEROP
       // If the source type is bridged to Objective-C, try to bridge.
       if (auto srcBridgeWitness = findBridgeWitness(srcType)) {
         return _dynamicCastValueToClassViaObjCBridgeable(dest, src, srcType,
@@ -2518,6 +2515,7 @@
                                                          srcBridgeWitness,
                                                          flags);
       }
+#endif
       return _fail(src, srcType, targetType, flags);
     }
 
@@ -2566,6 +2564,7 @@
         return _dynamicCastToAnyHashable(dest, src, srcType, targetType, flags);
       }
 
+#if SWIFT_OBJC_INTEROP
       // If the target type is bridged to Objective-C, try to bridge.
       if (auto targetBridgeWitness = findBridgeWitness(targetType)) {
         return _dynamicCastClassToValueViaObjCBridgeable(dest, src, srcType,
@@ -2574,7 +2573,6 @@
                                                          flags);
       }
       
-#if SWIFT_OBJC_INTEROP
       // If the source is an NSError, and the target is a bridgeable
       // Error, try to bridge.
       if (tryDynamicCastNSErrorToValue(dest, src, srcType, targetType, flags)) {
@@ -2673,6 +2671,7 @@
 /********************************** Bridging **********************************/
 /******************************************************************************/
 
+#if SWIFT_OBJC_INTEROP
 //===----------------------------------------------------------------------===//
 // Bridging to and from Objective-C
 //===----------------------------------------------------------------------===//
@@ -2893,13 +2892,6 @@
   return success;
 }
 
-#if !SWIFT_OBJC_INTEROP // _SwiftValue is a native class:
-
-
-
-#endif // !_SWIFT_OBJC_INTEROP
-
-#if SWIFT_OBJC_INTEROP
 static id bridgeAnythingNonVerbatimToObjectiveC(OpaqueValue *src,
                                                 const Metadata *srcType,
                                                 bool consume) {
@@ -3000,7 +2992,6 @@
   return bridgeAnythingNonVerbatimToObjectiveC(src, srcType,
                                                /*consume*/shouldConsume);
 }
-#endif
 
 //===--- Bridging helpers for the Swift stdlib ----------------------------===//
 // Functions that must discover and possibly use an arbitrary type's
@@ -3008,12 +2999,10 @@
 // documentation.
 //===----------------------------------------------------------------------===//
 
-#if SWIFT_OBJC_INTEROP
 #define BRIDGING_CONFORMANCE_SYM \
   MANGLE_SYM(s19_BridgeableMetatypeVs21_ObjectiveCBridgeablesWP)
 
 extern "C" const _ObjectiveCBridgeableWitnessTable BRIDGING_CONFORMANCE_SYM;
-#endif
 
 static const _ObjectiveCBridgeableWitnessTable *
 findBridgeWitness(const Metadata *T) {
@@ -3026,20 +3015,16 @@
   // that looks like a metatype value if the metatype can be bridged.
   switch (T->getKind()) {
   case MetadataKind::Metatype: {
-#if SWIFT_OBJC_INTEROP
     auto metaTy = static_cast<const MetatypeMetadata *>(T);
     if (metaTy->InstanceType->isAnyClass())
       return &BRIDGING_CONFORMANCE_SYM;
-#endif
     break;
   }
   case MetadataKind::ExistentialMetatype: {
-#if SWIFT_OBJC_INTEROP
     auto existentialMetaTy =
       static_cast<const ExistentialMetatypeMetadata *>(T);
     if (existentialMetaTy->isObjC())
       return &BRIDGING_CONFORMANCE_SYM;
-#endif
     break;
   }
 
@@ -3081,8 +3066,6 @@
   return nullptr;
 }
 
-#if SWIFT_OBJC_INTEROP
-
 // @_silgen_name("_bridgeNonVerbatimFromObjectiveCToAny")
 // func _bridgeNonVerbatimFromObjectiveCToAny(
 //     x: AnyObject,
@@ -3119,6 +3102,7 @@
       return true;
     }
   }
+  
   // Check if the value is a box containing a value of the desired type.
   if (auto srcBox = getAsSwiftValue((id)sourceValue)) {
     const Metadata *sourceType;
@@ -3150,7 +3134,6 @@
   OpaqueValue *destValue,
   const Metadata *nativeType_
 ) {
-  
   if (tryBridgeNonVerbatimFromObjectiveCUniversal(sourceValue, nativeType,
                                                   destValue))
     return;
@@ -3228,8 +3211,6 @@
     destValue, nativeType, nativeType, bridgeWitness);
 }
 
-#endif // SWIFT_OBJC_INTEROP
-
 // func _isBridgedNonVerbatimToObjectiveC<T>(_: T.Type) -> Bool
 // Called by inlined stdlib code.
 #define _isBridgedNonVerbatimToObjectiveC \
@@ -3242,6 +3223,7 @@
   auto bridgeWitness = findBridgeWitness(T);
   return (bool)bridgeWitness;
 }
+#endif
 
 // func _isClassOrObjCExistential<T>(x: T.Type) -> Bool
 SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERFACE
@@ -3270,55 +3252,6 @@
   return type->getKind() == MetadataKind::Optional;
 }
 
-#if !SWIFT_OBJC_INTEROP
-SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
-bool _swift_isOptional(OpaqueValue *src, const Metadata *type) {
-  return swift_isOptionalType(type);
-}
-
-SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
-HeapObject *_swift_extractDynamicValue(OpaqueValue *value, const Metadata *self) {
-  OpaqueValue *outValue;
-  const Metadata *outType;
-  bool canTake = false;
-  
-  findDynamicValueAndType(value, self, outValue, outType, canTake,
-                          /*isAnyObject*/ true,
-                          /*isExistentialMetatype*/ true);
-
-  if (!outType || (outType != self && outType->isAnyClass())) {
-    HeapObject *object = *(reinterpret_cast<HeapObject**>(outValue));
-    swift_retain(object);
-    return object;
-  }
-  
-  return nullptr;
-}
-
-SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
-HeapObject *_swift_bridgeToObjectiveCUsingProtocolIfPossible(
-  OpaqueValue *src, const Metadata *srcType) {
-  assert(!swift_isClassOrObjCExistentialTypeImpl(srcType));
-  
-  OpaqueValue *outValue;
-  const Metadata *outType;
-  bool canTake = false;
-  
-  findDynamicValueAndType(src, srcType, outValue, outType, canTake,
-                          /*isAnyObject*/ false,
-                          /*isExistentialMetatype*/ true);
-  
-  auto bridgeWitness = findBridgeWitness(outType);
-  if (bridgeWitness) {
-    auto bridgedObject =
-      bridgeWitness->bridgeToObjectiveC(outValue, outType, bridgeWitness);
-    return bridgedObject;
-  } else {
-    return nullptr;
-  }
-}
-#endif
-
 #define OVERRIDE_CASTING COMPATIBILITY_OVERRIDE
 #include "CompatibilityOverride.def"
 
diff --git a/test/Constraints/bridging_nonobjc.swift b/test/Constraints/bridging_nonobjc.swift
new file mode 100644
index 0000000..f2c06ee
--- /dev/null
+++ b/test/Constraints/bridging_nonobjc.swift
@@ -0,0 +1,5 @@
+// RUN: %target-swift-frontend -typecheck -verify %s -disable-objc-interop
+
+
+var x: Any = 1
+var y = x as AnyObject // expected-error{{not convertible}}
diff --git a/test/Interpreter/generic_casts.swift b/test/Interpreter/generic_casts.swift
index 4008fe1..0705141 100644
--- a/test/Interpreter/generic_casts.swift
+++ b/test/Interpreter/generic_casts.swift
@@ -158,6 +158,16 @@
 // Bridging
 print(allToAll(0, AnyObject.self)) // CHECK-NEXT: true
 
+// This will get bridged using _SwiftValue.
+struct NotBridged { var x: Int }
+print(allToAll(NotBridged(x: 0), AnyObject.self)) // CHECK-NEXT: true
+print(allToAll(NotBridged(x: 0), NSCopying.self)) // CHECK-NEXT: true
+
+// These casts fail (intentionally) even though _SwiftValue does
+// technically conform to these protocols through NSObject.
+print(allToAll(NotBridged(x: 0), CustomStringConvertible.self)) // CHECK-NEXT: false
+print(allToAll(NotBridged(x: 0), (AnyObject & CustomStringConvertible).self)) // CHECK-NEXT: false
+
 //
 // rdar://problem/19482567
 //
diff --git a/test/SILGen/generic_casts.swift b/test/SILGen/generic_casts.swift
index 74aace8..3a8e7fc 100644
--- a/test/SILGen/generic_casts.swift
+++ b/test/SILGen/generic_casts.swift
@@ -59,9 +59,11 @@
 <T:ClassBound, U:ClassBound>(_ t:T) -> U {
   return t as! U
   // Error bridging can change the identity of class-constrained archetypes.
-  // CHECK: unconditional_checked_cast_addr T in {{%.*}} : $*T to U in [[DOWNCAST_ADDR:%.*]] : $*U
-  // CHECK: [[DOWNCAST:%.*]] = load [take] [[DOWNCAST_ADDR]]
-  // CHECK: return [[DOWNCAST]] : $U
+  // CHECK-objc: unconditional_checked_cast_addr T in {{%.*}} : $*T to U in [[DOWNCAST_ADDR:%.*]] : $*U
+  // CHECK-objc: [[DOWNCAST:%.*]] = load [take] [[DOWNCAST_ADDR]]
+  // CHECK-objc: return [[DOWNCAST]] : $U
+
+  // CHECK-native: [[DOWNCAST:%.*]] = unconditional_checked_cast {{.*}} : $T to $U
 }
 
 // CHECK-LABEL: sil hidden @$S13generic_casts019class_archetype_is_c1_D0{{[_0-9a-zA-Z]*}}F
@@ -69,7 +71,8 @@
 <T:ClassBound, U:ClassBound>(_ t:T, u:U.Type) -> Bool {
   return t is U
   // Error bridging can change the identity of class-constrained archetypes.
-  // CHECK: checked_cast_addr_br {{.*}} T in {{%.*}} : $*T to U in {{%.*}} : $*U
+  // CHECK-objc: checked_cast_addr_br {{.*}} T in {{%.*}} : $*T to U in {{%.*}} : $*U
+  // CHECK-native: checked_cast_br {{.*}} : $T to $U
 }
 
 // CHECK-LABEL: sil hidden @$S13generic_casts38opaque_archetype_to_addr_only_concrete{{[_0-9a-zA-Z]*}}F
@@ -158,16 +161,19 @@
 func class_existential_to_class_archetype
 <T:ClassBound>(_ p:ClassBound) -> T {
   return p as! T
-  // CHECK: unconditional_checked_cast_addr ClassBound in {{%.*}} : $*ClassBound to T in [[DOWNCAST_ADDR:%.*]] : $*T
-  // CHECK: [[DOWNCAST:%.*]] = load [take] [[DOWNCAST_ADDR]]
-  // CHECK: return [[DOWNCAST]] : $T
+  // CHECK-objc: unconditional_checked_cast_addr ClassBound in {{%.*}} : $*ClassBound to T in [[DOWNCAST_ADDR:%.*]] : $*T
+  // CHECK-objc: [[DOWNCAST:%.*]] = load [take] [[DOWNCAST_ADDR]]
+  // CHECK-objc: return [[DOWNCAST]] : $T
+
+  // CHECK-native: [[DOWNCAST:%.*]] = unconditional_checked_cast {{.*}} : $ClassBound to $T
 }
 
 // CHECK-LABEL: sil hidden @$S13generic_casts021class_existential_is_C10_archetype{{[_0-9a-zA-Z]*}}F
 func class_existential_is_class_archetype
 <T:ClassBound>(_ p:ClassBound, _: T) -> Bool {
   return p is T
-  // CHECK: checked_cast_addr_br {{.*}} ClassBound in {{%.*}} : $*ClassBound to T in {{%.*}} : $*T
+  // CHECK-objc: checked_cast_addr_br {{.*}} ClassBound in {{%.*}} : $*ClassBound to T in {{%.*}} : $*T
+  // CHECK-native: checked_cast_br {{.*}} : $ClassBound to $T
 }
 
 // CHECK-LABEL: sil hidden @$S13generic_casts40opaque_existential_to_addr_only_concrete{{[_0-9a-zA-Z]*}}F
diff --git a/test/expr/cast/array_downcast.swift b/test/expr/cast/array_downcast.swift
index fddea8a..475036d 100644
--- a/test/expr/cast/array_downcast.swift
+++ b/test/expr/cast/array_downcast.swift
@@ -1,5 +1,7 @@
 // RUN: %target-typecheck-verify-swift
 
+// XFAIL: linux
+
 // FIXME: Should go into the standard library.
 public extension _ObjectiveCBridgeable {
   static func _unconditionallyBridgeFromObjectiveC(_ source: _ObjectiveCType?)
diff --git a/test/lit.cfg b/test/lit.cfg
index 54226e2..3b1b2e5 100644
--- a/test/lit.cfg
+++ b/test/lit.cfg
@@ -968,31 +968,35 @@
     config.target_run_simple_swift = (
         '%%empty-directory(%%t) && '
         '%s %s %%s -o %%t/a.out -module-name main && '
+        '%s %%t/a.out &&'
         '%s %%t/a.out'
-        % (config.target_build_swift, mcp_opt, config.target_run))
+        % (config.target_build_swift, mcp_opt, config.target_codesign, config.target_run))
     config.target_run_stdlib_swift = (
         '%%empty-directory(%%t) && '
         '%s %s %%s -o %%t/a.out -module-name main '
         '-Xfrontend -disable-access-control && '
+        '%s %%t/a.out &&'
         '%s %%t/a.out'
-        % (config.target_build_swift, mcp_opt, config.target_run))
+        % (config.target_build_swift, mcp_opt, config.target_codesign, config.target_run))
     config.target_run_simple_swiftgyb = (
         '%%empty-directory(%%t) && '
         '%%gyb %%s -o %%t/main.swift && '
         '%%line-directive %%t/main.swift -- '
         '%s %s %%t/main.swift -o %%t/a.out -module-name main && '
+        '%s %%t/a.out &&'
         '%%line-directive %%t/main.swift -- '
         '%s %%t/a.out'
-        % (config.target_build_swift, mcp_opt, config.target_run))
+        % (config.target_build_swift, mcp_opt, config.target_codesign, config.target_run))
     config.target_run_stdlib_swiftgyb = (
         '%%empty-directory(%%t) && '
         '%%gyb %%s -o %%t/main.swift && '
         '%%line-directive %%t/main.swift -- '
         '%s %s %%t/main.swift -o %%t/a.out -module-name main '
         '-Xfrontend -disable-access-control && '
+        '%s %%t/a.out &&'
         '%%line-directive %%t/main.swift -- '
         '%s %%t/a.out'
-        % (config.target_build_swift, mcp_opt, config.target_run))
+        % (config.target_build_swift, mcp_opt, config.target_codesign, config.target_run))
 
 subst_target_jit_run = ""
 if 'swift_interpreter' in config.available_features:
diff --git a/test/stmt/errors_nonobjc.swift b/test/stmt/errors_nonobjc.swift
new file mode 100644
index 0000000..7f710f7
--- /dev/null
+++ b/test/stmt/errors_nonobjc.swift
@@ -0,0 +1,18 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-swift-frontend -emit-module -module-name Foundation -o %t/Foundation.swiftmodule %S/Inputs/Foundation-with-NSError.swift
+// RUN: %target-swift-frontend -I %t -typecheck -verify %s
+// UNSUPPORTED: objc_interop
+
+import Foundation
+
+// Catching `as NSError` ought *not* to be exhaustive when ObjC interop is
+// disabled. It's just another error type.
+
+func bar() throws {}
+
+func foo() {
+  do {
+    try bar() // expected-error{{enclosing catch is not exhaustive}}
+  } catch _ as NSError {
+  }
+}
diff --git a/unittests/runtime/Stdlib.cpp b/unittests/runtime/Stdlib.cpp
index 03ed7d5..6495133 100644
--- a/unittests/runtime/Stdlib.cpp
+++ b/unittests/runtime/Stdlib.cpp
@@ -135,12 +135,7 @@
   abort();
 }
 
-SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
-bool swift_unboxFromSwiftValueWithType(OpaqueValue *source,
-                                       OpaqueValue *result,
-                                       const Metadata *destinationType) {
-  abort();
-}
+
 // ErrorObject
 
 SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL