diff --git a/docs/ClangCommandLineReference.rst b/docs/ClangCommandLineReference.rst
index d964e34..a7b485a 100644
--- a/docs/ClangCommandLineReference.rst
+++ b/docs/ClangCommandLineReference.rst
@@ -656,10 +656,6 @@
 
 Pass <arg> to the clang compiler
 
-.. option:: -fclang-abi-compat=<version>
-
-Attempt to match the ABI of Clang <version>
-
 .. option:: -fcomment-block-commands=<arg>,<arg2>...
 
 Treat each comma separated argument in <arg> as a documentation comment block command
diff --git a/include/clang/AST/DeclCXX.h b/include/clang/AST/DeclCXX.h
index 2f735c5..515cb77 100644
--- a/include/clang/AST/DeclCXX.h
+++ b/include/clang/AST/DeclCXX.h
@@ -375,7 +375,6 @@
     /// \brief These flags are \c true if a defaulted corresponding special
     /// member can't be fully analyzed without performing overload resolution.
     /// @{
-    unsigned NeedOverloadResolutionForCopyConstructor : 1;
     unsigned NeedOverloadResolutionForMoveConstructor : 1;
     unsigned NeedOverloadResolutionForMoveAssignment : 1;
     unsigned NeedOverloadResolutionForDestructor : 1;
@@ -384,7 +383,6 @@
     /// \brief These flags are \c true if an implicit defaulted corresponding
     /// special member would be defined as deleted.
     /// @{
-    unsigned DefaultedCopyConstructorIsDeleted : 1;
     unsigned DefaultedMoveConstructorIsDeleted : 1;
     unsigned DefaultedMoveAssignmentIsDeleted : 1;
     unsigned DefaultedDestructorIsDeleted : 1;
@@ -417,12 +415,6 @@
     /// constructor.
     unsigned HasDefaultedDefaultConstructor : 1;
 
-    /// \brief True if this class can be passed in a non-address-preserving
-    /// fashion (such as in registers) according to the C++ language rules.
-    /// This does not imply anything about how the ABI in use will actually
-    /// pass an object of this class.
-    unsigned CanPassInRegisters : 1;
-
     /// \brief True if a defaulted default constructor for this class would
     /// be constexpr.
     unsigned DefaultedDefaultConstructorIsConstexpr : 1;
@@ -819,50 +811,18 @@
     return data().FirstFriend.isValid();
   }
 
-  /// \brief \c true if a defaulted copy constructor for this class would be
-  /// deleted.
-  bool defaultedCopyConstructorIsDeleted() const {
-    assert((!needsOverloadResolutionForCopyConstructor() ||
-            (data().DeclaredSpecialMembers & SMF_CopyConstructor)) &&
-           "this property has not yet been computed by Sema");
-    return data().DefaultedCopyConstructorIsDeleted;
-  }
-
-  /// \brief \c true if a defaulted move constructor for this class would be
-  /// deleted.
-  bool defaultedMoveConstructorIsDeleted() const {
-    assert((!needsOverloadResolutionForMoveConstructor() ||
-            (data().DeclaredSpecialMembers & SMF_MoveConstructor)) &&
-           "this property has not yet been computed by Sema");
-    return data().DefaultedMoveConstructorIsDeleted;
-  }
-
-  /// \brief \c true if a defaulted destructor for this class would be deleted.
-  bool defaultedDestructorIsDeleted() const {
-    return !data().DefaultedDestructorIsDeleted;
-  }
-
-  /// \brief \c true if we know for sure that this class has a single,
-  /// accessible, unambiguous copy constructor that is not deleted.
-  bool hasSimpleCopyConstructor() const {
-    return !hasUserDeclaredCopyConstructor() &&
-           !data().DefaultedCopyConstructorIsDeleted;
-  }
-
   /// \brief \c true if we know for sure that this class has a single,
   /// accessible, unambiguous move constructor that is not deleted.
   bool hasSimpleMoveConstructor() const {
     return !hasUserDeclaredMoveConstructor() && hasMoveConstructor() &&
            !data().DefaultedMoveConstructorIsDeleted;
   }
-
   /// \brief \c true if we know for sure that this class has a single,
   /// accessible, unambiguous move assignment operator that is not deleted.
   bool hasSimpleMoveAssignment() const {
     return !hasUserDeclaredMoveAssignment() && hasMoveAssignment() &&
            !data().DefaultedMoveAssignmentIsDeleted;
   }
-
   /// \brief \c true if we know for sure that this class has an accessible
   /// destructor that is not deleted.
   bool hasSimpleDestructor() const {
@@ -918,16 +878,7 @@
   /// \brief Determine whether we need to eagerly declare a defaulted copy
   /// constructor for this class.
   bool needsOverloadResolutionForCopyConstructor() const {
-    // C++17 [class.copy.ctor]p6:
-    //   If the class definition declares a move constructor or move assignment
-    //   operator, the implicitly declared copy constructor is defined as
-    //   deleted.
-    // In MSVC mode, sometimes a declared move assignment does not delete an
-    // implicit copy constructor, so defer this choice to Sema.
-    if (data().UserDeclaredSpecialMembers &
-        (SMF_MoveConstructor | SMF_MoveAssignment))
-      return true;
-    return data().NeedOverloadResolutionForCopyConstructor;
+    return data().HasMutableFields;
   }
 
   /// \brief Determine whether an implicit copy constructor for this type
@@ -968,16 +919,7 @@
            needsImplicitMoveConstructor();
   }
 
-  /// \brief Set that we attempted to declare an implicit copy
-  /// constructor, but overload resolution failed so we deleted it.
-  void setImplicitCopyConstructorIsDeleted() {
-    assert((data().DefaultedCopyConstructorIsDeleted ||
-            needsOverloadResolutionForCopyConstructor()) &&
-           "Copy constructor should not be deleted");
-    data().DefaultedCopyConstructorIsDeleted = true;
-  }
-
-  /// \brief Set that we attempted to declare an implicit move
+  /// \brief Set that we attempted to declare an implicitly move
   /// constructor, but overload resolution failed so we deleted it.
   void setImplicitMoveConstructorIsDeleted() {
     assert((data().DefaultedMoveConstructorIsDeleted ||
@@ -1374,18 +1316,6 @@
     return data().HasIrrelevantDestructor;
   }
 
-  /// \brief Determine whether this class has at least one trivial, non-deleted
-  /// copy or move constructor.
-  bool canPassInRegisters() const {
-    return data().CanPassInRegisters;
-  }
-
-  /// \brief Set that we can pass this RecordDecl in registers.
-  // FIXME: This should be set as part of completeDefinition.
-  void setCanPassInRegisters(bool CanPass) {
-    data().CanPassInRegisters = CanPass;
-  }
-
   /// \brief Determine whether this class has a non-literal or/ volatile type
   /// non-static data member or base class.
   bool hasNonLiteralTypeFieldsOrBases() const {
diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td
index 80eb435..d4d8ed4 100644
--- a/include/clang/Driver/Options.td
+++ b/include/clang/Driver/Options.td
@@ -716,9 +716,6 @@
 def fbuiltin_module_map : Flag <["-"], "fbuiltin-module-map">, Group<f_Group>,
   Flags<[DriverOption]>, HelpText<"Load the clang builtins module map file.">;
 def fcaret_diagnostics : Flag<["-"], "fcaret-diagnostics">, Group<f_Group>;
-def fclang_abi_compat_EQ : Joined<["-"], "fclang-abi-compat=">, Group<f_clang_Group>,
-  Flags<[CC1Option]>, MetaVarName<"<version>">, Values<"<major>.<minor>,latest">,
-  HelpText<"Attempt to match the ABI of Clang <version>">;
 def fclasspath_EQ : Joined<["-"], "fclasspath=">, Group<f_Group>;
 def fcolor_diagnostics : Flag<["-"], "fcolor-diagnostics">, Group<f_Group>,
   Flags<[CoreOption, CC1Option]>, HelpText<"Use colors in diagnostics">;
diff --git a/include/clang/Frontend/CodeGenOptions.def b/include/clang/Frontend/CodeGenOptions.def
index eb1564e..8bfa46e 100644
--- a/include/clang/Frontend/CodeGenOptions.def
+++ b/include/clang/Frontend/CodeGenOptions.def
@@ -120,10 +120,6 @@
 ENUM_CODEGENOPT(ObjCDispatchMethod, ObjCDispatchMethodKind, 2, Legacy)
 CODEGENOPT(OmitLeafFramePointer , 1, 0) ///< Set when -momit-leaf-frame-pointer is
                                         ///< enabled.
-
-/// A version of Clang that we should attempt to be ABI-compatible with.
-ENUM_CODEGENOPT(ClangABICompat, ClangABI, 4, ClangABI::Latest)
-
 VALUE_CODEGENOPT(OptimizationLevel, 2, 0) ///< The -O[0-3] option specified.
 VALUE_CODEGENOPT(OptimizeSize, 2, 0) ///< If -Os (==1) or -Oz (==2) is specified.
 
diff --git a/include/clang/Frontend/CodeGenOptions.h b/include/clang/Frontend/CodeGenOptions.h
index 71730a2..22d5d3d 100644
--- a/include/clang/Frontend/CodeGenOptions.h
+++ b/include/clang/Frontend/CodeGenOptions.h
@@ -69,23 +69,6 @@
     LocalExecTLSModel
   };
 
-  /// Clang versions with different platform ABI conformance.
-  enum class ClangABI {
-    /// Attempt to be ABI-compatible with code generated by Clang 3.8.x
-    /// (SVN r257626). This causes <1 x long long> to be passed in an
-    /// integer register instead of an SSE register on x64_64.
-    Ver3_8,
-
-    /// Attempt to be ABI-compatible with code generated by Clang 4.0.x
-    /// (SVN r291814). This causes move operations to be ignored when
-    /// determining whether a class type can be passed or returned directly.
-    Ver4,
-
-    /// Conform to the underlying platform's C and C++ ABIs as closely
-    /// as we can.
-    Latest
-  };
-
   enum StructReturnConventionKind {
     SRCK_Default,  // No special option was passed.
     SRCK_OnStack,  // Small structs on the stack (-fpcc-struct-return).
diff --git a/lib/AST/ASTImporter.cpp b/lib/AST/ASTImporter.cpp
index 2c0bb11..6e33b98 100644
--- a/lib/AST/ASTImporter.cpp
+++ b/lib/AST/ASTImporter.cpp
@@ -956,16 +956,12 @@
     ToData.HasUninitializedFields = FromData.HasUninitializedFields;
     ToData.HasInheritedConstructor = FromData.HasInheritedConstructor;
     ToData.HasInheritedAssignment = FromData.HasInheritedAssignment;
-    ToData.NeedOverloadResolutionForCopyConstructor
-      = FromData.NeedOverloadResolutionForCopyConstructor;
     ToData.NeedOverloadResolutionForMoveConstructor
       = FromData.NeedOverloadResolutionForMoveConstructor;
     ToData.NeedOverloadResolutionForMoveAssignment
       = FromData.NeedOverloadResolutionForMoveAssignment;
     ToData.NeedOverloadResolutionForDestructor
       = FromData.NeedOverloadResolutionForDestructor;
-    ToData.DefaultedCopyConstructorIsDeleted
-      = FromData.DefaultedCopyConstructorIsDeleted;
     ToData.DefaultedMoveConstructorIsDeleted
       = FromData.DefaultedMoveConstructorIsDeleted;
     ToData.DefaultedMoveAssignmentIsDeleted
@@ -977,7 +973,6 @@
       = FromData.HasConstexprNonCopyMoveConstructor;
     ToData.HasDefaultedDefaultConstructor
       = FromData.HasDefaultedDefaultConstructor;
-    ToData.CanPassInRegisters = FromData.CanPassInRegisters;
     ToData.DefaultedDefaultConstructorIsConstexpr
       = FromData.DefaultedDefaultConstructorIsConstexpr;
     ToData.HasConstexprDefaultConstructor
diff --git a/lib/AST/DeclCXX.cpp b/lib/AST/DeclCXX.cpp
index 5782b7b..1caceab 100644
--- a/lib/AST/DeclCXX.cpp
+++ b/lib/AST/DeclCXX.cpp
@@ -55,18 +55,15 @@
       HasOnlyCMembers(true), HasInClassInitializer(false),
       HasUninitializedReferenceMember(false), HasUninitializedFields(false),
       HasInheritedConstructor(false), HasInheritedAssignment(false),
-      NeedOverloadResolutionForCopyConstructor(false),
       NeedOverloadResolutionForMoveConstructor(false),
       NeedOverloadResolutionForMoveAssignment(false),
       NeedOverloadResolutionForDestructor(false),
-      DefaultedCopyConstructorIsDeleted(false),
       DefaultedMoveConstructorIsDeleted(false),
       DefaultedMoveAssignmentIsDeleted(false),
       DefaultedDestructorIsDeleted(false), HasTrivialSpecialMembers(SMF_All),
       DeclaredNonTrivialSpecialMembers(0), HasIrrelevantDestructor(true),
       HasConstexprNonCopyMoveConstructor(false),
       HasDefaultedDefaultConstructor(false),
-      CanPassInRegisters(true),
       DefaultedDefaultConstructorIsConstexpr(true),
       HasConstexprDefaultConstructor(false),
       HasNonLiteralTypeFieldsOrBases(false), ComputedVisibleConversions(false),
@@ -355,10 +352,8 @@
       setHasVolatileMember(true);
 
     // Keep track of the presence of mutable fields.
-    if (BaseClassDecl->hasMutableFields()) {
+    if (BaseClassDecl->hasMutableFields())
       data().HasMutableFields = true;
-      data().NeedOverloadResolutionForCopyConstructor = true;
-    }
 
     if (BaseClassDecl->hasUninitializedReferenceMember())
       data().HasUninitializedReferenceMember = true;
@@ -411,8 +406,6 @@
   //    -- a direct or virtual base class B that cannot be copied/moved [...]
   //    -- a non-static data member of class type M (or array thereof)
   //       that cannot be copied or moved [...]
-  if (!Subobj->hasSimpleCopyConstructor())
-    data().NeedOverloadResolutionForCopyConstructor = true;
   if (!Subobj->hasSimpleMoveConstructor())
     data().NeedOverloadResolutionForMoveConstructor = true;
 
@@ -433,7 +426,6 @@
   //    -- any non-static data member has a type with a destructor
   //       that is deleted or inaccessible from the defaulted [ctor or dtor].
   if (!Subobj->hasSimpleDestructor()) {
-    data().NeedOverloadResolutionForCopyConstructor = true;
     data().NeedOverloadResolutionForMoveConstructor = true;
     data().NeedOverloadResolutionForDestructor = true;
   }
@@ -719,10 +711,8 @@
       data().IsStandardLayout = false;
 
     // Keep track of the presence of mutable fields.
-    if (Field->isMutable()) {
+    if (Field->isMutable())
       data().HasMutableFields = true;
-      data().NeedOverloadResolutionForCopyConstructor = true;
-    }
 
     // C++11 [class.union]p8, DR1460:
     //   If X is a union, a non-static data member of X that is not an anonymous
@@ -766,12 +756,6 @@
       //   A standard-layout class is a class that:
       //    -- has no non-static data members of type [...] reference,
       data().IsStandardLayout = false;
-
-      // C++1z [class.copy.ctor]p10:
-      //   A defaulted copy constructor for a class X is defined as deleted if X has:
-      //    -- a non-static data member of rvalue reference type
-      if (T->isRValueReferenceType())
-        data().DefaultedCopyConstructorIsDeleted = true;
     }
 
     if (!Field->hasInClassInitializer() && !Field->isMutable()) {
@@ -825,10 +809,6 @@
         // We may need to perform overload resolution to determine whether a
         // field can be moved if it's const or volatile qualified.
         if (T.getCVRQualifiers() & (Qualifiers::Const | Qualifiers::Volatile)) {
-          // We need to care about 'const' for the copy constructor because an
-          // implicit copy constructor might be declared with a non-const
-          // parameter.
-          data().NeedOverloadResolutionForCopyConstructor = true;
           data().NeedOverloadResolutionForMoveConstructor = true;
           data().NeedOverloadResolutionForMoveAssignment = true;
         }
@@ -839,8 +819,6 @@
         //    -- X is a union-like class that has a variant member with a
         //       non-trivial [corresponding special member]
         if (isUnion()) {
-          if (FieldRec->hasNonTrivialCopyConstructor())
-            data().DefaultedCopyConstructorIsDeleted = true;
           if (FieldRec->hasNonTrivialMoveConstructor())
             data().DefaultedMoveConstructorIsDeleted = true;
           if (FieldRec->hasNonTrivialMoveAssignment())
@@ -852,8 +830,6 @@
         // For an anonymous union member, our overload resolution will perform
         // overload resolution for its members.
         if (Field->isAnonymousStructOrUnion()) {
-          data().NeedOverloadResolutionForCopyConstructor |=
-              FieldRec->data().NeedOverloadResolutionForCopyConstructor;
           data().NeedOverloadResolutionForMoveConstructor |=
               FieldRec->data().NeedOverloadResolutionForMoveConstructor;
           data().NeedOverloadResolutionForMoveAssignment |=
@@ -939,10 +915,8 @@
         }
         
         // Keep track of the presence of mutable fields.
-        if (FieldRec->hasMutableFields()) {
+        if (FieldRec->hasMutableFields())
           data().HasMutableFields = true;
-          data().NeedOverloadResolutionForCopyConstructor = true;
-        }
 
         // C++11 [class.copy]p13:
         //   If the implicitly-defined constructor would satisfy the
@@ -1476,7 +1450,7 @@
 
 void CXXRecordDecl::completeDefinition(CXXFinalOverriderMap *FinalOverriders) {
   RecordDecl::completeDefinition();
-
+  
   // If the class may be abstract (but hasn't been marked as such), check for
   // any pure final overriders.
   if (mayBeAbstract()) {
diff --git a/lib/CodeGen/ABIInfo.h b/lib/CodeGen/ABIInfo.h
index 575506d..e4dce2f 100644
--- a/lib/CodeGen/ABIInfo.h
+++ b/lib/CodeGen/ABIInfo.h
@@ -24,7 +24,6 @@
 
 namespace clang {
   class ASTContext;
-  class CodeGenOptions;
   class TargetInfo;
 
 namespace CodeGen {
@@ -69,7 +68,6 @@
     llvm::LLVMContext &getVMContext() const;
     const llvm::DataLayout &getDataLayout() const;
     const TargetInfo &getTarget() const;
-    const CodeGenOptions &getCodeGenOpts() const;
 
     /// Return the calling convention to use for system runtime
     /// functions.
diff --git a/lib/CodeGen/CGCXXABI.cpp b/lib/CodeGen/CGCXXABI.cpp
index 0332586..e29e525 100644
--- a/lib/CodeGen/CGCXXABI.cpp
+++ b/lib/CodeGen/CGCXXABI.cpp
@@ -30,9 +30,38 @@
 }
 
 bool CGCXXABI::canCopyArgument(const CXXRecordDecl *RD) const {
+  // If RD has a non-trivial move or copy constructor, we cannot copy the
+  // argument.
+  if (RD->hasNonTrivialCopyConstructor() || RD->hasNonTrivialMoveConstructor())
+    return false;
+
+  // If RD has a non-trivial destructor, we cannot copy the argument.
+  if (RD->hasNonTrivialDestructor())
+    return false;
+
   // We can only copy the argument if there exists at least one trivial,
   // non-deleted copy or move constructor.
-  return RD->canPassInRegisters();
+  // FIXME: This assumes that all lazily declared copy and move constructors are
+  // not deleted.  This assumption might not be true in some corner cases.
+  bool CopyDeleted = false;
+  bool MoveDeleted = false;
+  for (const CXXConstructorDecl *CD : RD->ctors()) {
+    if (CD->isCopyConstructor() || CD->isMoveConstructor()) {
+      assert(CD->isTrivial());
+      // We had at least one undeleted trivial copy or move ctor.  Return
+      // directly.
+      if (!CD->isDeleted())
+        return true;
+      if (CD->isCopyConstructor())
+        CopyDeleted = true;
+      else
+        MoveDeleted = true;
+    }
+  }
+
+  // If all trivial copy and move constructors are deleted, we cannot copy the
+  // argument.
+  return !(CopyDeleted && MoveDeleted);
 }
 
 llvm::Constant *CGCXXABI::GetBogusMemberPointer(QualType T) {
diff --git a/lib/CodeGen/CodeGenTypes.cpp b/lib/CodeGen/CodeGenTypes.cpp
index 9306c4f..5ed9291 100644
--- a/lib/CodeGen/CodeGenTypes.cpp
+++ b/lib/CodeGen/CodeGenTypes.cpp
@@ -44,10 +44,6 @@
     delete &*I++;
 }
 
-const CodeGenOptions &CodeGenTypes::getCodeGenOpts() const {
-  return CGM.getCodeGenOpts();
-}
-
 void CodeGenTypes::addRecordTypeName(const RecordDecl *RD,
                                      llvm::StructType *Ty,
                                      StringRef suffix) {
diff --git a/lib/CodeGen/CodeGenTypes.h b/lib/CodeGen/CodeGenTypes.h
index 9d0e3de..f0b97eb 100644
--- a/lib/CodeGen/CodeGenTypes.h
+++ b/lib/CodeGen/CodeGenTypes.h
@@ -178,7 +178,6 @@
   const TargetInfo &getTarget() const { return Target; }
   CGCXXABI &getCXXABI() const { return TheCXXABI; }
   llvm::LLVMContext &getLLVMContext() { return TheModule.getContext(); }
-  const CodeGenOptions &getCodeGenOpts() const;
 
   /// ConvertType - Convert type T into a llvm::Type.
   llvm::Type *ConvertType(QualType T);
diff --git a/lib/CodeGen/ItaniumCXXABI.cpp b/lib/CodeGen/ItaniumCXXABI.cpp
index bd4cb9a..c82b967 100644
--- a/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/lib/CodeGen/ItaniumCXXABI.cpp
@@ -62,20 +62,12 @@
 
   bool classifyReturnType(CGFunctionInfo &FI) const override;
 
-  bool passClassIndirect(const CXXRecordDecl *RD) const {
-    // Clang <= 4 used the pre-C++11 rule, which ignores move operations.
-    // The PS4 platform ABI follows the behavior of Clang 3.2.
-    if (CGM.getCodeGenOpts().getClangABICompat() <=
-            CodeGenOptions::ClangABI::Ver4 ||
-        CGM.getTriple().getOS() == llvm::Triple::PS4)
-      return RD->hasNonTrivialDestructor() ||
-             RD->hasNonTrivialCopyConstructor();
-    return !canCopyArgument(RD);
-  }
-
   RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const override {
-    // If C++ prohibits us from making a copy, pass by address.
-    if (passClassIndirect(RD))
+    // Structures with either a non-trivial destructor or a non-trivial
+    // copy constructor are always indirect.
+    // FIXME: Use canCopyArgument() when it is fixed to handle lazily declared
+    // special members.
+    if (RD->hasNonTrivialDestructor() || RD->hasNonTrivialCopyConstructor())
       return RAA_Indirect;
     return RAA_Default;
   }
@@ -1006,8 +998,10 @@
   if (!RD)
     return false;
 
-  // If C++ prohibits us from making a copy, return by address.
-  if (passClassIndirect(RD)) {
+  // Return indirectly if we have a non-trivial copy ctor or non-trivial dtor.
+  // FIXME: Use canCopyArgument() when it is fixed to handle lazily declared
+  // special members.
+  if (RD->hasNonTrivialDestructor() || RD->hasNonTrivialCopyConstructor()) {
     auto Align = CGM.getContext().getTypeAlignInChars(FI.getReturnType());
     FI.getReturnInfo() = ABIArgInfo::getIndirect(Align, /*ByVal=*/false);
     return true;
diff --git a/lib/CodeGen/MicrosoftCXXABI.cpp b/lib/CodeGen/MicrosoftCXXABI.cpp
index 1bd2937..78b510b 100644
--- a/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -819,44 +819,46 @@
     return RAA_Default;
 
   case llvm::Triple::x86_64:
-    // If a class has a destructor, we'd really like to pass it indirectly
+    // Win64 passes objects with non-trivial copy ctors indirectly.
+    if (RD->hasNonTrivialCopyConstructor())
+      return RAA_Indirect;
+
+    // If an object has a destructor, we'd really like to pass it indirectly
     // because it allows us to elide copies.  Unfortunately, MSVC makes that
     // impossible for small types, which it will pass in a single register or
     // stack slot. Most objects with dtors are large-ish, so handle that early.
     // We can't call out all large objects as being indirect because there are
     // multiple x64 calling conventions and the C++ ABI code shouldn't dictate
     // how we pass large POD types.
-    //
-    // Note: This permits small classes with nontrivial destructors to be
-    // passed in registers, which is non-conforming.
     if (RD->hasNonTrivialDestructor() &&
         getContext().getTypeSize(RD->getTypeForDecl()) > 64)
       return RAA_Indirect;
 
-    // If a class has at least one non-deleted, trivial copy constructor, it
-    // is passed according to the C ABI. Otherwise, it is passed indirectly.
-    //
-    // Note: This permits classes with non-trivial copy or move ctors to be
-    // passed in registers, so long as they *also* have a trivial copy ctor,
-    // which is non-conforming.
-    if (RD->needsImplicitCopyConstructor()) {
-      // If the copy ctor has not yet been declared, we can read its triviality
-      // off the AST.
-      if (!RD->defaultedCopyConstructorIsDeleted() &&
-          RD->hasTrivialCopyConstructor())
-        return RAA_Default;
-    } else {
-      // Otherwise, we need to find the copy constructor(s) and ask.
-      for (const CXXConstructorDecl *CD : RD->ctors()) {
-        if (CD->isCopyConstructor()) {
-          // We had at least one nondeleted trivial copy ctor.  Return directly.
-          if (!CD->isDeleted() && CD->isTrivial())
-            return RAA_Default;
-        }
+    // If this is true, the implicit copy constructor that Sema would have
+    // created would not be deleted. FIXME: We should provide a more direct way
+    // for CodeGen to ask whether the constructor was deleted.
+    if (!RD->hasUserDeclaredCopyConstructor() &&
+        !RD->hasUserDeclaredMoveConstructor() &&
+        !RD->needsOverloadResolutionForMoveConstructor() &&
+        !RD->hasUserDeclaredMoveAssignment() &&
+        !RD->needsOverloadResolutionForMoveAssignment())
+      return RAA_Default;
+
+    // Otherwise, Sema should have created an implicit copy constructor if
+    // needed.
+    assert(!RD->needsImplicitCopyConstructor());
+
+    // We have to make sure the trivial copy constructor isn't deleted.
+    for (const CXXConstructorDecl *CD : RD->ctors()) {
+      if (CD->isCopyConstructor()) {
+        assert(CD->isTrivial());
+        // We had at least one undeleted trivial copy ctor.  Return directly.
+        if (!CD->isDeleted())
+          return RAA_Default;
       }
     }
 
-    // We have no trivial, non-deleted copy constructor.
+    // The trivial copy constructor was deleted.  Return indirectly.
     return RAA_Indirect;
   }
 
diff --git a/lib/CodeGen/TargetInfo.cpp b/lib/CodeGen/TargetInfo.cpp
index fd58fb7..546439c 100644
--- a/lib/CodeGen/TargetInfo.cpp
+++ b/lib/CodeGen/TargetInfo.cpp
@@ -183,11 +183,7 @@
   return CGT.getTarget();
 }
 
-const CodeGenOptions &ABIInfo::getCodeGenOpts() const {
-  return CGT.getCodeGenOpts();
-}
-
-bool ABIInfo::isAndroid() const { return getTarget().getTriple().isAndroid(); }
+bool ABIInfo:: isAndroid() const { return getTarget().getTriple().isAndroid(); }
 
 bool ABIInfo::isHomogeneousAggregateBaseType(QualType Ty) const {
   return false;
@@ -2099,14 +2095,9 @@
     return !getTarget().getTriple().isOSDarwin();
   }
 
-  /// GCC classifies <1 x long long> as SSE but some platform ABIs choose to
-  /// classify it as INTEGER (for compatibility with older clang compilers).
+  /// GCC classifies <1 x long long> as SSE but compatibility with older clang
+  // compilers require us to classify it as INTEGER.
   bool classifyIntegerMMXAsSSE() const {
-    // Clang <= 3.8 did not do this.
-    if (getCodeGenOpts().getClangABICompat() <=
-        CodeGenOptions::ClangABI::Ver3_8)
-      return false;
-
     const llvm::Triple &Triple = getTarget().getTriple();
     if (Triple.isOSDarwin() || Triple.getOS() == llvm::Triple::PS4)
       return false;
diff --git a/lib/Driver/ToolChains/Clang.cpp b/lib/Driver/ToolChains/Clang.cpp
index a5544a8..def01ae 100644
--- a/lib/Driver/ToolChains/Clang.cpp
+++ b/lib/Driver/ToolChains/Clang.cpp
@@ -2864,9 +2864,6 @@
 
   addPGOAndCoverageFlags(C, D, Output, Args, CmdArgs);
 
-  if (auto *ABICompatArg = Args.getLastArg(options::OPT_fclang_abi_compat_EQ))
-    ABICompatArg->render(Args, CmdArgs);
-
   // Add runtime flag for PS4 when PGO or Coverage are enabled.
   if (getToolChain().getTriple().isPS4CPU())
     PS4cpu::addProfileRTArgs(getToolChain(), Args, CmdArgs);
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index 76009a2..2bb2946 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -573,33 +573,6 @@
   if (!Opts.ProfileInstrumentUsePath.empty())
     setPGOUseInstrumentor(Opts, Opts.ProfileInstrumentUsePath);
 
-  if (Arg *A = Args.getLastArg(OPT_fclang_abi_compat_EQ)) {
-    Opts.setClangABICompat(CodeGenOptions::ClangABI::Latest);
-
-    StringRef Ver = A->getValue();
-    std::pair<StringRef, StringRef> VerParts = Ver.split('.');
-    unsigned Major, Minor = 0;
-
-    // Check the version number is valid: either 3.x (0 <= x <= 9) or
-    // y or y.0 (4 <= y <= current version).
-    if (!VerParts.first.startswith("0") &&
-        !VerParts.first.getAsInteger(10, Major) &&
-        3 <= Major && Major <= CLANG_VERSION_MAJOR &&
-        (Major == 3 ? VerParts.second.size() == 1 &&
-                      !VerParts.second.getAsInteger(10, Minor)
-                    : VerParts.first.size() == Ver.size() ||
-                      VerParts.second == "0")) {
-      // Got a valid version number.
-      if (Major == 3 && Minor <= 8)
-        Opts.setClangABICompat(CodeGenOptions::ClangABI::Ver3_8);
-      else if (Major <= 4)
-        Opts.setClangABICompat(CodeGenOptions::ClangABI::Ver4);
-    } else if (Ver != "latest") {
-      Diags.Report(diag::err_drv_invalid_value)
-          << A->getAsString(Args) << A->getValue();
-    }
-  }
-
   Opts.CoverageMapping =
       Args.hasFlag(OPT_fcoverage_mapping, OPT_fno_coverage_mapping, false);
   Opts.DumpCoverageMapping = Args.hasArg(OPT_dump_coverage_mapping);
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index def1469..e4e384b 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -5726,53 +5726,6 @@
   }
 }
 
-/// Determine whether a type is permitted to be passed or returned in
-/// registers, per C++ [class.temporary]p3.
-static bool computeCanPassInRegisters(Sema &S, CXXRecordDecl *D) {
-  if (D->isDependentType() || D->isInvalidDecl())
-    return false;
-
-  // Per C++ [class.temporary]p3, the relevant condition is:
-  //   each copy constructor, move constructor, and destructor of X is
-  //   either trivial or deleted, and X has at least one non-deleted copy
-  //   or move constructor
-  bool HasNonDeletedCopyOrMove = false;
-
-  if (D->needsImplicitCopyConstructor() &&
-      !D->defaultedCopyConstructorIsDeleted()) {
-    if (!D->hasTrivialCopyConstructor())
-      return false;
-    HasNonDeletedCopyOrMove = true; 
-  }
-
-  if (S.getLangOpts().CPlusPlus11 && D->needsImplicitMoveConstructor() &&
-      !D->defaultedMoveConstructorIsDeleted()) {
-    if (!D->hasTrivialMoveConstructor())
-      return false;
-    HasNonDeletedCopyOrMove = true;
-  }
-
-  if (D->needsImplicitDestructor() && !D->defaultedDestructorIsDeleted() &&
-      !D->hasTrivialDestructor())
-    return false;
-
-  for (const CXXMethodDecl *MD : D->methods()) {
-    if (MD->isDeleted())
-      continue;
-
-    auto *CD = dyn_cast<CXXConstructorDecl>(MD);
-    if (CD && CD->isCopyOrMoveConstructor())
-      HasNonDeletedCopyOrMove = true;
-    else if (!isa<CXXDestructorDecl>(MD))
-      continue;
-
-    if (!MD->isTrivial())
-      return false;
-  }
-
-  return HasNonDeletedCopyOrMove;
-}
-
 /// \brief Perform semantic checks on a class definition that has been
 /// completing, introducing implicitly-declared members, checking for
 /// abstract types, etc.
@@ -5917,8 +5870,6 @@
   }
 
   checkClassLevelDLLAttribute(Record);
-
-  Record->setCanPassInRegisters(computeCanPassInRegisters(*this, Record));
 }
 
 /// Look up the special member function that would be called by a special
@@ -7545,7 +7496,8 @@
               reinterpret_cast<Decl**>(FieldCollector->getCurFields()),
               FieldCollector->getCurNumFields()), LBrac, RBrac, AttrList);
 
-  CheckCompletedCXXClass(dyn_cast_or_null<CXXRecordDecl>(TagDecl));
+  CheckCompletedCXXClass(
+                        dyn_cast_or_null<CXXRecordDecl>(TagDecl));
 }
 
 /// AddImplicitlyDeclaredMembersToClass - Adds any implicitly-declared
@@ -11980,10 +11932,8 @@
   Scope *S = getScopeForContext(ClassDecl);
   CheckImplicitSpecialMemberDeclaration(S, CopyConstructor);
 
-  if (ShouldDeleteSpecialMember(CopyConstructor, CXXCopyConstructor)) {
-    ClassDecl->setImplicitCopyConstructorIsDeleted();
+  if (ShouldDeleteSpecialMember(CopyConstructor, CXXCopyConstructor))
     SetDeclDeleted(CopyConstructor, ClassLoc);
-  }
 
   if (S)
     PushOnScopeChains(CopyConstructor, S, false);
diff --git a/lib/Serialization/ASTReaderDecl.cpp b/lib/Serialization/ASTReaderDecl.cpp
index 8e9e24d..93b5e20 100644
--- a/lib/Serialization/ASTReaderDecl.cpp
+++ b/lib/Serialization/ASTReaderDecl.cpp
@@ -1561,11 +1561,9 @@
   Data.HasUninitializedFields = Record.readInt();
   Data.HasInheritedConstructor = Record.readInt();
   Data.HasInheritedAssignment = Record.readInt();
-  Data.NeedOverloadResolutionForCopyConstructor = Record.readInt();
   Data.NeedOverloadResolutionForMoveConstructor = Record.readInt();
   Data.NeedOverloadResolutionForMoveAssignment = Record.readInt();
   Data.NeedOverloadResolutionForDestructor = Record.readInt();
-  Data.DefaultedCopyConstructorIsDeleted = Record.readInt();
   Data.DefaultedMoveConstructorIsDeleted = Record.readInt();
   Data.DefaultedMoveAssignmentIsDeleted = Record.readInt();
   Data.DefaultedDestructorIsDeleted = Record.readInt();
@@ -1574,7 +1572,6 @@
   Data.HasIrrelevantDestructor = Record.readInt();
   Data.HasConstexprNonCopyMoveConstructor = Record.readInt();
   Data.HasDefaultedDefaultConstructor = Record.readInt();
-  Data.CanPassInRegisters = Record.readInt();
   Data.DefaultedDefaultConstructorIsConstexpr = Record.readInt();
   Data.HasConstexprDefaultConstructor = Record.readInt();
   Data.HasNonLiteralTypeFieldsOrBases = Record.readInt();
@@ -1702,11 +1699,9 @@
   MATCH_FIELD(HasUninitializedFields)
   MATCH_FIELD(HasInheritedConstructor)
   MATCH_FIELD(HasInheritedAssignment)
-  MATCH_FIELD(NeedOverloadResolutionForCopyConstructor)
   MATCH_FIELD(NeedOverloadResolutionForMoveConstructor)
   MATCH_FIELD(NeedOverloadResolutionForMoveAssignment)
   MATCH_FIELD(NeedOverloadResolutionForDestructor)
-  MATCH_FIELD(DefaultedCopyConstructorIsDeleted)
   MATCH_FIELD(DefaultedMoveConstructorIsDeleted)
   MATCH_FIELD(DefaultedMoveAssignmentIsDeleted)
   MATCH_FIELD(DefaultedDestructorIsDeleted)
@@ -1715,7 +1710,6 @@
   MATCH_FIELD(HasIrrelevantDestructor)
   OR_FIELD(HasConstexprNonCopyMoveConstructor)
   OR_FIELD(HasDefaultedDefaultConstructor)
-  MATCH_FIELD(CanPassInRegisters)
   MATCH_FIELD(DefaultedDefaultConstructorIsConstexpr)
   OR_FIELD(HasConstexprDefaultConstructor)
   MATCH_FIELD(HasNonLiteralTypeFieldsOrBases)
diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index ec03a87..07ad0db 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -5888,11 +5888,9 @@
   Record->push_back(Data.HasUninitializedFields);
   Record->push_back(Data.HasInheritedConstructor);
   Record->push_back(Data.HasInheritedAssignment);
-  Record->push_back(Data.NeedOverloadResolutionForCopyConstructor);
   Record->push_back(Data.NeedOverloadResolutionForMoveConstructor);
   Record->push_back(Data.NeedOverloadResolutionForMoveAssignment);
   Record->push_back(Data.NeedOverloadResolutionForDestructor);
-  Record->push_back(Data.DefaultedCopyConstructorIsDeleted);
   Record->push_back(Data.DefaultedMoveConstructorIsDeleted);
   Record->push_back(Data.DefaultedMoveAssignmentIsDeleted);
   Record->push_back(Data.DefaultedDestructorIsDeleted);
@@ -5901,7 +5899,6 @@
   Record->push_back(Data.HasIrrelevantDestructor);
   Record->push_back(Data.HasConstexprNonCopyMoveConstructor);
   Record->push_back(Data.HasDefaultedDefaultConstructor);
-  Record->push_back(Data.CanPassInRegisters);
   Record->push_back(Data.DefaultedDefaultConstructorIsConstexpr);
   Record->push_back(Data.HasConstexprDefaultConstructor);
   Record->push_back(Data.HasNonLiteralTypeFieldsOrBases);
diff --git a/test/CodeGenCXX/clang-abi-compat.cpp b/test/CodeGenCXX/clang-abi-compat.cpp
deleted file mode 100644
index 409c721..0000000
--- a/test/CodeGenCXX/clang-abi-compat.cpp
+++ /dev/null
@@ -1,19 +0,0 @@
-// RUN: %clang_cc1 -std=c++17 -triple x86_64-linux-gnu -fclang-abi-compat=3.0 %s -emit-llvm -o - | FileCheck --check-prefix=PRE39 --check-prefix=PRE5 %s
-// RUN: %clang_cc1 -std=c++17 -triple x86_64-linux-gnu -fclang-abi-compat=3.8 %s -emit-llvm -o - | FileCheck --check-prefix=PRE39 --check-prefix=PRE5 %s
-// RUN: %clang_cc1 -std=c++17 -triple x86_64-linux-gnu -fclang-abi-compat=3.9 %s -emit-llvm -o - | FileCheck --check-prefix=V39 --check-prefix=PRE5 %s
-// RUN: %clang_cc1 -std=c++17 -triple x86_64-linux-gnu -fclang-abi-compat=4.0 %s -emit-llvm -o - | FileCheck --check-prefix=V39 --check-prefix=PRE5 %s
-// RUN: %clang_cc1 -std=c++17 -triple x86_64-linux-gnu -fclang-abi-compat=5 %s -emit-llvm -o - | FileCheck --check-prefix=V39 --check-prefix=V5 %s
-// RUN: %clang_cc1 -std=c++17 -triple x86_64-linux-gnu -fclang-abi-compat=latest %s -emit-llvm -o - | FileCheck --check-prefix=V39 --check-prefix=V5 %s
-
-typedef __attribute__((vector_size(8))) long long v1xi64;
-void clang39(v1xi64) {}
-// PRE39: @_Z7clang39Dv1_x(i64
-// V39: @_Z7clang39Dv1_x(double
-
-struct A {
-  A(const A&) = default;
-  A(A&&);
-};
-void clang5(A) {}
-// PRE5: @_Z6clang51A()
-// V5: @_Z6clang51A(%{{.*}}*
diff --git a/test/CodeGenCXX/uncopyable-args.cpp b/test/CodeGenCXX/uncopyable-args.cpp
index 66d67e4..307a5cf 100644
--- a/test/CodeGenCXX/uncopyable-args.cpp
+++ b/test/CodeGenCXX/uncopyable-args.cpp
@@ -1,8 +1,5 @@
-// RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-unknown -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK --check-prefix=NEWABI
-// RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-unknown -fclang-abi-compat=4.0 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK --check-prefix=OLDABI
-// RUN: %clang_cc1 -std=c++11 -triple x86_64-scei-ps4 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK --check-prefix=OLDABI
-// RUN: %clang_cc1 -std=c++11 -triple x86_64-windows-msvc -emit-llvm -o - %s -fms-compatibility -fms-compatibility-version=18 | FileCheck %s -check-prefix=WIN64 -check-prefix=WIN64-18
-// RUN: %clang_cc1 -std=c++11 -triple x86_64-windows-msvc -emit-llvm -o - %s -fms-compatibility -fms-compatibility-version=19 | FileCheck %s -check-prefix=WIN64 -check-prefix=WIN64-19
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-unknown -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-windows-msvc -emit-llvm -o - %s | FileCheck %s -check-prefix=WIN64
 
 namespace trivial {
 // Trivial structs should be passed directly.
@@ -55,13 +52,12 @@
 void bar() {
   foo({});
 }
-// CHECK-LABEL: define void @_ZN9move_ctor3barEv()
-// CHECK: call void @_Z{{.*}}C1Ev(
-// CHECK-NOT: call
-// NEWABI: call void @_ZN9move_ctor3fooENS_1AE(%"struct.move_ctor::A"* %{{.*}})
-// OLDABI: call void @_ZN9move_ctor3fooENS_1AE(i8* %{{.*}})
-// NEWABI-LABEL: declare void @_ZN9move_ctor3fooENS_1AE(%"struct.move_ctor::A"*)
-// OLDABI-LABEL: declare void @_ZN9move_ctor3fooENS_1AE(i8*)
+// FIXME: The copy ctor is implicitly deleted.
+// CHECK-DISABLED-LABEL: define void @_ZN9move_ctor3barEv()
+// CHECK-DISABLED: call void @_Z{{.*}}C1Ev(
+// CHECK-DISABLED-NOT: call
+// CHECK-DISABLED: call void @_ZN9move_ctor3fooENS_1AE(%"struct.move_ctor::A"* %{{.*}})
+// CHECK-DISABLED-LABEL: declare void @_ZN9move_ctor3fooENS_1AE(%"struct.move_ctor::A"*)
 
 // WIN64-LABEL: declare void @"\01?foo@move_ctor@@YAXUA@1@@Z"(%"struct.move_ctor::A"*)
 }
@@ -77,13 +73,12 @@
 void bar() {
   foo({});
 }
-// CHECK-LABEL: define void @_ZN11all_deleted3barEv()
-// CHECK: call void @_Z{{.*}}C1Ev(
-// CHECK-NOT: call
-// NEWABI: call void @_ZN11all_deleted3fooENS_1AE(%"struct.all_deleted::A"* %{{.*}})
-// OLDABI: call void @_ZN11all_deleted3fooENS_1AE(i8* %{{.*}})
-// NEWABI-LABEL: declare void @_ZN11all_deleted3fooENS_1AE(%"struct.all_deleted::A"*)
-// OLDABI-LABEL: declare void @_ZN11all_deleted3fooENS_1AE(i8*)
+// FIXME: The copy ctor is deleted.
+// CHECK-DISABLED-LABEL: define void @_ZN11all_deleted3barEv()
+// CHECK-DISABLED: call void @_Z{{.*}}C1Ev(
+// CHECK-DISABLED-NOT: call
+// CHECK-DISABLED: call void @_ZN11all_deleted3fooENS_1AE(%"struct.all_deleted::A"* %{{.*}})
+// CHECK-DISABLED-LABEL: declare void @_ZN11all_deleted3fooENS_1AE(%"struct.all_deleted::A"*)
 
 // WIN64-LABEL: declare void @"\01?foo@all_deleted@@YAXUA@1@@Z"(%"struct.all_deleted::A"*)
 }
@@ -98,17 +93,14 @@
 void bar() {
   foo({});
 }
-// CHECK-LABEL: define void @_ZN18implicitly_deleted3barEv()
-// CHECK: call void @_Z{{.*}}C1Ev(
-// CHECK-NOT: call
-// NEWABI: call void @_ZN18implicitly_deleted3fooENS_1AE(%"struct.implicitly_deleted::A"* %{{.*}})
-// OLDABI: call void @_ZN18implicitly_deleted3fooENS_1AE(i8* %{{.*}})
-// NEWABI-LABEL: declare void @_ZN18implicitly_deleted3fooENS_1AE(%"struct.implicitly_deleted::A"*)
-// OLDABI-LABEL: declare void @_ZN18implicitly_deleted3fooENS_1AE(i8*)
+// FIXME: The copy and move ctors are implicitly deleted.
+// CHECK-DISABLED-LABEL: define void @_ZN18implicitly_deleted3barEv()
+// CHECK-DISABLED: call void @_Z{{.*}}C1Ev(
+// CHECK-DISABLED-NOT: call
+// CHECK-DISABLED: call void @_ZN18implicitly_deleted3fooENS_1AE(%"struct.implicitly_deleted::A"* %{{.*}})
+// CHECK-DISABLED-LABEL: declare void @_ZN18implicitly_deleted3fooENS_1AE(%"struct.implicitly_deleted::A"*)
 
-// In MSVC 2013, the copy ctor is not deleted by a move assignment. In MSVC 2015, it is.
-// WIN64-18-LABEL: declare void @"\01?foo@implicitly_deleted@@YAXUA@1@@Z"(i64
-// WIN64-19-LABEL: declare void @"\01?foo@implicitly_deleted@@YAXUA@1@@Z"(%"struct.implicitly_deleted::A"*)
+// WIN64-LABEL: declare void @"\01?foo@implicitly_deleted@@YAXUA@1@@Z"(%"struct.implicitly_deleted::A"*)
 }
 
 namespace one_deleted {
@@ -121,13 +113,12 @@
 void bar() {
   foo({});
 }
-// CHECK-LABEL: define void @_ZN11one_deleted3barEv()
-// CHECK: call void @_Z{{.*}}C1Ev(
-// CHECK-NOT: call
-// NEWABI: call void @_ZN11one_deleted3fooENS_1AE(%"struct.one_deleted::A"* %{{.*}})
-// OLDABI: call void @_ZN11one_deleted3fooENS_1AE(i8* %{{.*}})
-// NEWABI-LABEL: declare void @_ZN11one_deleted3fooENS_1AE(%"struct.one_deleted::A"*)
-// OLDABI-LABEL: declare void @_ZN11one_deleted3fooENS_1AE(i8*)
+// FIXME: The copy constructor is implicitly deleted.
+// CHECK-DISABLED-LABEL: define void @_ZN11one_deleted3barEv()
+// CHECK-DISABLED: call void @_Z{{.*}}C1Ev(
+// CHECK-DISABLED-NOT: call
+// CHECK-DISABLED: call void @_ZN11one_deleted3fooENS_1AE(%"struct.one_deleted::A"* %{{.*}})
+// CHECK-DISABLED-LABEL: declare void @_ZN11one_deleted3fooENS_1AE(%"struct.one_deleted::A"*)
 
 // WIN64-LABEL: declare void @"\01?foo@one_deleted@@YAXUA@1@@Z"(%"struct.one_deleted::A"*)
 }
@@ -204,12 +195,12 @@
 void bar() {
   foo({});
 }
-// CHECK-LABEL: define void @_ZN14two_copy_ctors3barEv()
-// CHECK: call void @_Z{{.*}}C1Ev(
-// NEWABI: call void @_ZN14two_copy_ctors3fooENS_1BE(%"struct.two_copy_ctors::B"* %{{.*}})
-// OLDABI: call void @_ZN14two_copy_ctors3fooENS_1BE(%"struct.two_copy_ctors::B"* byval
-// NEWABI-LABEL: declare void @_ZN14two_copy_ctors3fooENS_1BE(%"struct.two_copy_ctors::B"*)
-// OLDABI-LABEL: declare void @_ZN14two_copy_ctors3fooENS_1BE(%"struct.two_copy_ctors::B"* byval
+// FIXME: This class has a non-trivial copy ctor and a trivial copy ctor.  It's
+// not clear whether we should pass by address or in registers.
+// CHECK-DISABLED-LABEL: define void @_ZN14two_copy_ctors3barEv()
+// CHECK-DISABLED: call void @_Z{{.*}}C1Ev(
+// CHECK-DISABLED: call void @_ZN14two_copy_ctors3fooENS_1BE(%"struct.two_copy_ctors::B"* %{{.*}})
+// CHECK-DISABLED-LABEL: declare void @_ZN14two_copy_ctors3fooENS_1BE(%"struct.two_copy_ctors::B"*)
 
 // WIN64-LABEL: declare void @"\01?foo@two_copy_ctors@@YAXUB@1@@Z"(%"struct.two_copy_ctors::B"*)
 }
@@ -221,8 +212,6 @@
   void *p;
 };
 void *foo(A a) { return a.p; }
-// NEWABI-LABEL: define i8* @_ZN15definition_only3fooENS_1AE(%"struct.definition_only::A"*
-// OLDABI-LABEL: define i8* @_ZN15definition_only3fooENS_1AE(i8*
 // WIN64-LABEL: define i8* @"\01?foo@definition_only@@YAPEAXUA@1@@Z"(%"struct.definition_only::A"*
 }
 
@@ -237,8 +226,6 @@
   B b;
 };
 void *foo(A a) { return a.b.p; }
-// NEWABI-LABEL: define i8* @_ZN17deleted_by_member3fooENS_1AE(%"struct.deleted_by_member::A"*
-// OLDABI-LABEL: define i8* @_ZN17deleted_by_member3fooENS_1AE(i8*
 // WIN64-LABEL: define i8* @"\01?foo@deleted_by_member@@YAPEAXUA@1@@Z"(%"struct.deleted_by_member::A"*
 }
 
@@ -252,8 +239,6 @@
   A();
 };
 void *foo(A a) { return a.p; }
-// NEWABI-LABEL: define i8* @_ZN15deleted_by_base3fooENS_1AE(%"struct.deleted_by_base::A"*
-// OLDABI-LABEL: define i8* @_ZN15deleted_by_base3fooENS_1AE(i8*
 // WIN64-LABEL: define i8* @"\01?foo@deleted_by_base@@YAPEAXUA@1@@Z"(%"struct.deleted_by_base::A"*
 }
 
@@ -268,8 +253,6 @@
   B b;
 };
 void *foo(A a) { return a.b.p; }
-// NEWABI-LABEL: define i8* @_ZN22deleted_by_member_copy3fooENS_1AE(%"struct.deleted_by_member_copy::A"*
-// OLDABI-LABEL: define i8* @_ZN22deleted_by_member_copy3fooENS_1AE(i8*
 // WIN64-LABEL: define i8* @"\01?foo@deleted_by_member_copy@@YAPEAXUA@1@@Z"(%"struct.deleted_by_member_copy::A"*
 }
 
@@ -283,8 +266,6 @@
   A();
 };
 void *foo(A a) { return a.p; }
-// NEWABI-LABEL: define i8* @_ZN20deleted_by_base_copy3fooENS_1AE(%"struct.deleted_by_base_copy::A"*
-// OLDABI-LABEL: define i8* @_ZN20deleted_by_base_copy3fooENS_1AE(i8*
 // WIN64-LABEL: define i8* @"\01?foo@deleted_by_base_copy@@YAPEAXUA@1@@Z"(%"struct.deleted_by_base_copy::A"*
 }
 
@@ -294,77 +275,6 @@
   A(const A &o) = delete;
   void *p;
 };
-// NEWABI-LABEL: define i8* @_ZN15explicit_delete3fooENS_1AE(%"struct.explicit_delete::A"*
-// OLDABI-LABEL: define i8* @_ZN15explicit_delete3fooENS_1AE(i8*
 // WIN64-LABEL: define i8* @"\01?foo@explicit_delete@@YAPEAXUA@1@@Z"(%"struct.explicit_delete::A"*
 void *foo(A a) { return a.p; }
 }
-
-namespace implicitly_deleted_copy_ctor {
-struct A {
-  // No move ctor due to copy assignment.
-  A &operator=(const A&);
-  // Deleted copy ctor due to rvalue ref member.
-  int &&ref;
-};
-// NEWABI-LABEL: define {{.*}} @_ZN28implicitly_deleted_copy_ctor3fooENS_1AE(%"struct.implicitly_deleted_copy_ctor::A"*
-// OLDABI-LABEL: define {{.*}} @_ZN28implicitly_deleted_copy_ctor3fooENS_1AE(i32*
-// WIN64-LABEL: define {{.*}} @"\01?foo@implicitly_deleted_copy_ctor@@YAAEAHUA@1@@Z"(%"struct.implicitly_deleted_copy_ctor::A"*
-int &foo(A a) { return a.ref; }
-
-struct B {
-  // Passed direct: has non-deleted trivial copy ctor.
-  B &operator=(const B&);
-  int &ref;
-};
-int &foo(B b) { return b.ref; }
-// CHECK-LABEL: define {{.*}} @_ZN28implicitly_deleted_copy_ctor3fooENS_1BE(i32*
-// WIN64-LABEL: define {{.*}} @"\01?foo@implicitly_deleted_copy_ctor@@YAAEAHUB@1@@Z"(i64
-
-struct X { X(const X&); };
-struct Y { Y(const Y&) = default; };
-
-union C {
-  C &operator=(const C&);
-  // Passed indirect: copy ctor deleted due to variant member with nontrivial copy ctor.
-  X x;
-  int n;
-};
-int foo(C c) { return c.n; }
-// CHECK-LABEL: define {{.*}} @_ZN28implicitly_deleted_copy_ctor3fooENS_1CE(%"union.implicitly_deleted_copy_ctor::C"*
-// WIN64-LABEL: define {{.*}} @"\01?foo@implicitly_deleted_copy_ctor@@YAHTC@1@@Z"(%"union.implicitly_deleted_copy_ctor::C"*
-
-struct D {
-  D &operator=(const D&);
-  // Passed indirect: copy ctor deleted due to variant member with nontrivial copy ctor.
-  union {
-    X x;
-    int n;
-  };
-};
-int foo(D d) { return d.n; }
-// CHECK-LABEL: define {{.*}} @_ZN28implicitly_deleted_copy_ctor3fooENS_1DE(%"struct.implicitly_deleted_copy_ctor::D"*
-// WIN64-LABEL: define {{.*}} @"\01?foo@implicitly_deleted_copy_ctor@@YAHUD@1@@Z"(%"struct.implicitly_deleted_copy_ctor::D"*
-
-union E {
-  // Passed direct: has non-deleted trivial copy ctor.
-  E &operator=(const E&);
-  Y y;
-  int n;
-};
-int foo(E e) { return e.n; }
-// CHECK-LABEL: define {{.*}} @_ZN28implicitly_deleted_copy_ctor3fooENS_1EE(i32
-// WIN64-LABEL: define {{.*}} @"\01?foo@implicitly_deleted_copy_ctor@@YAHTE@1@@Z"(i32
-
-struct F {
-  // Passed direct: has non-deleted trivial copy ctor.
-  F &operator=(const F&);
-  union {
-    Y y;
-    int n;
-  };
-};
-int foo(F f) { return f.n; }
-// CHECK-LABEL: define {{.*}} @_ZN28implicitly_deleted_copy_ctor3fooENS_1FE(i32
-// WIN64-LABEL: define {{.*}} @"\01?foo@implicitly_deleted_copy_ctor@@YAHUF@1@@Z"(i32
-}
diff --git a/test/Driver/flags.c b/test/Driver/flags.c
index 656ac41..ff60caf 100644
--- a/test/Driver/flags.c
+++ b/test/Driver/flags.c
@@ -24,6 +24,3 @@
 
 // RUN: %clang -target armv7-apple-darwin10 -### -S -mno-implicit-float -mimplicit-float %s 2>&1 | FileCheck -check-prefix=TEST8 %s
 // TEST8-NOT: "-no-implicit-float"
-
-// RUN: %clang -target x86_64-linux-gnu -### -c -fclang-abi-compat=3.2 %s 2>&1 | FileCheck -check-prefix=TEST9 %s
-// TEST9: "-fclang-abi-compat=3.2"
diff --git a/test/Frontend/clang-abi-compat.cpp b/test/Frontend/clang-abi-compat.cpp
deleted file mode 100644
index 7ee9464..0000000
--- a/test/Frontend/clang-abi-compat.cpp
+++ /dev/null
@@ -1,15 +0,0 @@
-// RUN: not %clang_cc1 -fclang-abi-compat=banana %s -fsyntax-only 2>&1 | FileCheck --check-prefix=INVALID %s
-// RUN: not %clang_cc1 -fclang-abi-compat=2.9 %s -fsyntax-only 2>&1 | FileCheck --check-prefix=INVALID %s
-// RUN: not %clang_cc1 -fclang-abi-compat=8 %s -fsyntax-only 2>&1 | FileCheck --check-prefix=INVALID %s
-// RUN: not %clang_cc1 -fclang-abi-compat=3.10 %s -fsyntax-only 2>&1 | FileCheck --check-prefix=INVALID %s
-// RUN: not %clang_cc1 -fclang-abi-compat=4.1 %s -fsyntax-only 2>&1 | FileCheck --check-prefix=INVALID %s
-// RUN: not %clang_cc1 -fclang-abi-compat=04 %s -fsyntax-only 2>&1 | FileCheck --check-prefix=INVALID %s
-// RUN: not %clang_cc1 -fclang-abi-compat=4. %s -fsyntax-only 2>&1 | FileCheck --check-prefix=INVALID %s
-// RUN: not %clang_cc1 -fclang-abi-compat=4.00 %s -fsyntax-only 2>&1 | FileCheck --check-prefix=INVALID %s
-// INVALID: error: invalid value '{{.*}}' in '-fclang-abi-compat={{.*}}'
-//
-// RUN: %clang_cc1 -fclang-abi-compat=3.0 %s -fsyntax-only
-// RUN: %clang_cc1 -fclang-abi-compat=3.9 %s -fsyntax-only
-// RUN: %clang_cc1 -fclang-abi-compat=4 %s -fsyntax-only
-// RUN: %clang_cc1 -fclang-abi-compat=4.0 %s -fsyntax-only
-// RUN: %clang_cc1 -fclang-abi-compat=latest %s -fsyntax-only
diff --git a/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp b/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
index 7bc8421..6037127 100644
--- a/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
+++ b/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
@@ -1108,35 +1108,26 @@
 }
 
 TEST(ConstructorDeclaration, Kinds) {
-  EXPECT_TRUE(matches(
-      "struct S { S(); };",
-      cxxConstructorDecl(isDefaultConstructor(), unless(isImplicit()))));
-  EXPECT_TRUE(notMatches(
-      "struct S { S(); };",
-      cxxConstructorDecl(isCopyConstructor(), unless(isImplicit()))));
-  EXPECT_TRUE(notMatches(
-      "struct S { S(); };",
-      cxxConstructorDecl(isMoveConstructor(), unless(isImplicit()))));
+  EXPECT_TRUE(matches("struct S { S(); };",
+                      cxxConstructorDecl(isDefaultConstructor())));
+  EXPECT_TRUE(notMatches("struct S { S(); };",
+                         cxxConstructorDecl(isCopyConstructor())));
+  EXPECT_TRUE(notMatches("struct S { S(); };",
+                         cxxConstructorDecl(isMoveConstructor())));
 
-  EXPECT_TRUE(notMatches(
-      "struct S { S(const S&); };",
-      cxxConstructorDecl(isDefaultConstructor(), unless(isImplicit()))));
-  EXPECT_TRUE(matches(
-      "struct S { S(const S&); };",
-      cxxConstructorDecl(isCopyConstructor(), unless(isImplicit()))));
-  EXPECT_TRUE(notMatches(
-      "struct S { S(const S&); };",
-      cxxConstructorDecl(isMoveConstructor(), unless(isImplicit()))));
+  EXPECT_TRUE(notMatches("struct S { S(const S&); };",
+                         cxxConstructorDecl(isDefaultConstructor())));
+  EXPECT_TRUE(matches("struct S { S(const S&); };",
+                      cxxConstructorDecl(isCopyConstructor())));
+  EXPECT_TRUE(notMatches("struct S { S(const S&); };",
+                         cxxConstructorDecl(isMoveConstructor())));
 
-  EXPECT_TRUE(notMatches(
-      "struct S { S(S&&); };",
-      cxxConstructorDecl(isDefaultConstructor(), unless(isImplicit()))));
-  EXPECT_TRUE(notMatches(
-      "struct S { S(S&&); };",
-      cxxConstructorDecl(isCopyConstructor(), unless(isImplicit()))));
-  EXPECT_TRUE(matches(
-      "struct S { S(S&&); };",
-      cxxConstructorDecl(isMoveConstructor(), unless(isImplicit()))));
+  EXPECT_TRUE(notMatches("struct S { S(S&&); };",
+                         cxxConstructorDecl(isDefaultConstructor())));
+  EXPECT_TRUE(notMatches("struct S { S(S&&); };",
+                         cxxConstructorDecl(isCopyConstructor())));
+  EXPECT_TRUE(matches("struct S { S(S&&); };",
+                      cxxConstructorDecl(isMoveConstructor())));
 }
 
 TEST(ConstructorDeclaration, IsUserProvided) {