diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 2c58e27363c1..88b7680e4f73 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -711,6 +711,9 @@ def fbuiltin : Flag<["-"], "fbuiltin">, Group<f_Group>;
 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/clang/include/clang/Frontend/CodeGenOptions.def b/clang/include/clang/Frontend/CodeGenOptions.def
index c9040e7e4018..a806c4876510 100644
--- a/clang/include/clang/Frontend/CodeGenOptions.def
+++ b/clang/include/clang/Frontend/CodeGenOptions.def
@@ -120,6 +120,10 @@ CODEGENOPT(NoZeroInitializedInBSS , 1, 0) ///< -fno-zero-initialized-in-bss.
 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/clang/include/clang/Frontend/CodeGenOptions.h b/clang/include/clang/Frontend/CodeGenOptions.h
index 22d5d3d16ee2..71730a21dbe2 100644
--- a/clang/include/clang/Frontend/CodeGenOptions.h
+++ b/clang/include/clang/Frontend/CodeGenOptions.h
@@ -69,6 +69,23 @@ public:
     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/clang/lib/CodeGen/ABIInfo.h b/clang/lib/CodeGen/ABIInfo.h
index e4dce2f2a004..575506da84d4 100644
--- a/clang/lib/CodeGen/ABIInfo.h
+++ b/clang/lib/CodeGen/ABIInfo.h
@@ -24,6 +24,7 @@ namespace llvm {
 
 namespace clang {
   class ASTContext;
+  class CodeGenOptions;
   class TargetInfo;
 
 namespace CodeGen {
@@ -68,6 +69,7 @@ namespace swiftcall {
     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/clang/lib/CodeGen/CodeGenTypes.cpp b/clang/lib/CodeGen/CodeGenTypes.cpp
index 4ba0ba863c9e..adc3b9b4c83c 100644
--- a/clang/lib/CodeGen/CodeGenTypes.cpp
+++ b/clang/lib/CodeGen/CodeGenTypes.cpp
@@ -44,6 +44,10 @@ CodeGenTypes::~CodeGenTypes() {
     delete &*I++;
 }
 
+const CodeGenOptions &CodeGenTypes::getCodeGenOpts() const {
+  return CGM.getCodeGenOpts();
+}
+
 void CodeGenTypes::addRecordTypeName(const RecordDecl *RD,
                                      llvm::StructType *Ty,
                                      StringRef suffix) {
diff --git a/clang/lib/CodeGen/CodeGenTypes.h b/clang/lib/CodeGen/CodeGenTypes.h
index f0b97ebde1c2..9d0e3ded23e4 100644
--- a/clang/lib/CodeGen/CodeGenTypes.h
+++ b/clang/lib/CodeGen/CodeGenTypes.h
@@ -178,6 +178,7 @@ public:
   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/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 5c33f8c1afac..d78c032cec88 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -62,9 +62,20 @@ public:
 
   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 (!canCopyArgument(RD))
+    if (passClassIndirect(RD))
       return RAA_Indirect;
     return RAA_Default;
   }
@@ -1012,7 +1023,7 @@ bool ItaniumCXXABI::classifyReturnType(CGFunctionInfo &FI) const {
     return false;
 
   // If C++ prohibits us from making a copy, return by address.
-  if (!canCopyArgument(RD)) {
+  if (passClassIndirect(RD)) {
     auto Align = CGM.getContext().getTypeAlignInChars(FI.getReturnType());
     FI.getReturnInfo() = ABIArgInfo::getIndirect(Align, /*ByVal=*/false);
     return true;
diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index 64ee31f83d30..77b9b4caab5d 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -184,7 +184,11 @@ const TargetInfo &ABIInfo::getTarget() const {
   return CGT.getTarget();
 }
 
-bool ABIInfo:: isAndroid() const { return getTarget().getTriple().isAndroid(); }
+const CodeGenOptions &ABIInfo::getCodeGenOpts() const {
+  return CGT.getCodeGenOpts();
+}
+
+bool ABIInfo::isAndroid() const { return getTarget().getTriple().isAndroid(); }
 
 bool ABIInfo::isHomogeneousAggregateBaseType(QualType Ty) const {
   return false;
@@ -2112,9 +2116,14 @@ class X86_64ABIInfo : public SwiftABIInfo {
     return !getTarget().getTriple().isOSDarwin();
   }
 
-  /// GCC classifies <1 x long long> as SSE but compatibility with older clang
-  // compilers require us to classify it as INTEGER.
+  /// GCC classifies <1 x long long> as SSE but some platform ABIs choose to
+  /// classify it as INTEGER (for compatibility with older clang compilers).
   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/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index fa768b70c53e..47b9256f6c41 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -2933,6 +2933,9 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
 
   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/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index aea3af982859..abf6b0b302fe 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -573,6 +573,33 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   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/clang/test/CodeGenCXX/clang-abi-compat.cpp b/clang/test/CodeGenCXX/clang-abi-compat.cpp
new file mode 100644
index 000000000000..409c72108f64
--- /dev/null
+++ b/clang/test/CodeGenCXX/clang-abi-compat.cpp
@@ -0,0 +1,19 @@
+// 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/clang/test/CodeGenCXX/uncopyable-args.cpp b/clang/test/CodeGenCXX/uncopyable-args.cpp
index ef7168cdaaf7..66d67e4a34d5 100644
--- a/clang/test/CodeGenCXX/uncopyable-args.cpp
+++ b/clang/test/CodeGenCXX/uncopyable-args.cpp
@@ -1,4 +1,6 @@
-// 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-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
 
@@ -56,8 +58,10 @@ void bar() {
 // CHECK-LABEL: define void @_ZN9move_ctor3barEv()
 // CHECK: call void @_Z{{.*}}C1Ev(
 // CHECK-NOT: call
-// CHECK: call void @_ZN9move_ctor3fooENS_1AE(%"struct.move_ctor::A"* %{{.*}})
-// CHECK-LABEL: declare void @_ZN9move_ctor3fooENS_1AE(%"struct.move_ctor::A"*)
+// 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*)
 
 // WIN64-LABEL: declare void @"\01?foo@move_ctor@@YAXUA@1@@Z"(%"struct.move_ctor::A"*)
 }
@@ -76,8 +80,10 @@ void bar() {
 // CHECK-LABEL: define void @_ZN11all_deleted3barEv()
 // CHECK: call void @_Z{{.*}}C1Ev(
 // CHECK-NOT: call
-// CHECK: call void @_ZN11all_deleted3fooENS_1AE(%"struct.all_deleted::A"* %{{.*}})
-// CHECK-LABEL: declare void @_ZN11all_deleted3fooENS_1AE(%"struct.all_deleted::A"*)
+// 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*)
 
 // WIN64-LABEL: declare void @"\01?foo@all_deleted@@YAXUA@1@@Z"(%"struct.all_deleted::A"*)
 }
@@ -95,8 +101,10 @@ void bar() {
 // CHECK-LABEL: define void @_ZN18implicitly_deleted3barEv()
 // CHECK: call void @_Z{{.*}}C1Ev(
 // CHECK-NOT: call
-// CHECK: call void @_ZN18implicitly_deleted3fooENS_1AE(%"struct.implicitly_deleted::A"* %{{.*}})
-// CHECK-LABEL: declare void @_ZN18implicitly_deleted3fooENS_1AE(%"struct.implicitly_deleted::A"*)
+// 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*)
 
 // 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
@@ -116,8 +124,10 @@ void bar() {
 // CHECK-LABEL: define void @_ZN11one_deleted3barEv()
 // CHECK: call void @_Z{{.*}}C1Ev(
 // CHECK-NOT: call
-// CHECK: call void @_ZN11one_deleted3fooENS_1AE(%"struct.one_deleted::A"* %{{.*}})
-// CHECK-LABEL: declare void @_ZN11one_deleted3fooENS_1AE(%"struct.one_deleted::A"*)
+// 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*)
 
 // WIN64-LABEL: declare void @"\01?foo@one_deleted@@YAXUA@1@@Z"(%"struct.one_deleted::A"*)
 }
@@ -196,8 +206,10 @@ void bar() {
 }
 // CHECK-LABEL: define void @_ZN14two_copy_ctors3barEv()
 // CHECK: call void @_Z{{.*}}C1Ev(
-// CHECK: call void @_ZN14two_copy_ctors3fooENS_1BE(%"struct.two_copy_ctors::B"* %{{.*}})
-// CHECK-LABEL: declare void @_ZN14two_copy_ctors3fooENS_1BE(%"struct.two_copy_ctors::B"*)
+// 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
 
 // WIN64-LABEL: declare void @"\01?foo@two_copy_ctors@@YAXUB@1@@Z"(%"struct.two_copy_ctors::B"*)
 }
@@ -209,7 +221,8 @@ struct A {
   void *p;
 };
 void *foo(A a) { return a.p; }
-// CHECK-LABEL: define i8* @_ZN15definition_only3fooENS_1AE(%"struct.definition_only::A"*
+// 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"*
 }
 
@@ -224,7 +237,8 @@ struct A {
   B b;
 };
 void *foo(A a) { return a.b.p; }
-// CHECK-LABEL: define i8* @_ZN17deleted_by_member3fooENS_1AE(%"struct.deleted_by_member::A"*
+// 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"*
 }
 
@@ -238,7 +252,8 @@ struct A : B {
   A();
 };
 void *foo(A a) { return a.p; }
-// CHECK-LABEL: define i8* @_ZN15deleted_by_base3fooENS_1AE(%"struct.deleted_by_base::A"*
+// 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"*
 }
 
@@ -253,7 +268,8 @@ struct A {
   B b;
 };
 void *foo(A a) { return a.b.p; }
-// CHECK-LABEL: define i8* @_ZN22deleted_by_member_copy3fooENS_1AE(%"struct.deleted_by_member_copy::A"*
+// 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"*
 }
 
@@ -267,7 +283,8 @@ struct A : B {
   A();
 };
 void *foo(A a) { return a.p; }
-// CHECK-LABEL: define i8* @_ZN20deleted_by_base_copy3fooENS_1AE(%"struct.deleted_by_base_copy::A"*
+// 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"*
 }
 
@@ -277,7 +294,8 @@ struct A {
   A(const A &o) = delete;
   void *p;
 };
-// CHECK-LABEL: define i8* @_ZN15explicit_delete3fooENS_1AE(%"struct.explicit_delete::A"*
+// 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; }
 }
@@ -289,7 +307,8 @@ struct A {
   // Deleted copy ctor due to rvalue ref member.
   int &&ref;
 };
-// CHECK-LABEL: define {{.*}} @_ZN28implicitly_deleted_copy_ctor3fooENS_1AE(%"struct.implicitly_deleted_copy_ctor::A"*
+// 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; }
 
diff --git a/clang/test/Driver/flags.c b/clang/test/Driver/flags.c
index ff60caf2e0f3..656ac41a944f 100644
--- a/clang/test/Driver/flags.c
+++ b/clang/test/Driver/flags.c
@@ -24,3 +24,6 @@
 
 // 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/clang/test/Frontend/clang-abi-compat.cpp b/clang/test/Frontend/clang-abi-compat.cpp
new file mode 100644
index 000000000000..7ee94646b6d7
--- /dev/null
+++ b/clang/test/Frontend/clang-abi-compat.cpp
@@ -0,0 +1,15 @@
+// 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