diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -98,6 +98,8 @@
                "Objective-C auto-synthesized properties")
 BENIGN_LANGOPT(EncodeExtendedBlockSig , 1, 0,
                "Encoding extended block type signature")
+BENIGN_LANGOPT(EncodeCXXClassTemplateSpec , 1, 0,
+               "Fully encode c++ class template specialization")
 BENIGN_LANGOPT(ObjCInferRelatedResultType , 1, 1,
                "Objective-C related result type inference")
 LANGOPT(AppExt , 1, 0, "Objective-C App Extension")
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -2104,6 +2104,13 @@
 def fobjc_arc : Flag<["-"], "fobjc-arc">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Synthesize retain and release calls for Objective-C pointers">;
 def fno_objc_arc : Flag<["-"], "fno-objc-arc">, Group<f_Group>;
+def fobjc_encode_cxx_class_template_spec :
+  Flag<["-"], "fobjc-encode-cxx-class-template-spec">, Group<f_Group>,
+  Flags<[CC1Option]>,
+  HelpText<"Fully encode c++ class template specialization">,
+  MarshallingInfoFlag<LangOpts<"EncodeCXXClassTemplateSpec">>;
+def fno_objc_encode_cxx_class_template_spec :
+  Flag<["-"], "fno-objc-encode-cxx-class-template-spec">, Group<f_Group>;
 defm objc_convert_messages_to_runtime_calls : BoolFOption<"objc-convert-messages-to-runtime-calls",
   CodeGenOpts<"ObjCConvertMessagesToRuntimeCalls">, DefaultTrue,
   NegFlag<SetFalse, [CC1Option]>, PosFlag<SetTrue>>;
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -7305,6 +7305,40 @@
   S += llvm::utostr(FD->getBitWidthValue(*Ctx));
 }
 
+// Helper function for determining whether the encoded type string would include
+// a template specialization type.
+static bool hasTemplateSpecializationInEncodedString(const Type *T,
+                                                     bool VisitBasesAndFields) {
+  T = T->getBaseElementTypeUnsafe();
+
+  if (auto *PT = T->getAs<PointerType>())
+    return hasTemplateSpecializationInEncodedString(
+        PT->getPointeeType().getTypePtr(), false);
+
+  auto *CXXRD = T->getAsCXXRecordDecl();
+
+  if (!CXXRD)
+    return false;
+
+  if (isa<ClassTemplateSpecializationDecl>(CXXRD))
+    return true;
+
+  if (!CXXRD->hasDefinition() || !VisitBasesAndFields)
+    return false;
+
+  for (auto B : CXXRD->bases())
+    if (hasTemplateSpecializationInEncodedString(B.getType().getTypePtr(),
+                                                 true))
+      return true;
+
+  for (auto *FD : CXXRD->fields())
+    if (hasTemplateSpecializationInEncodedString(FD->getType().getTypePtr(),
+                                                 true))
+      return true;
+
+  return false;
+}
+
 // FIXME: Use SmallString for accumulating string.
 void ASTContext::getObjCEncodingForTypeImpl(QualType T, std::string &S,
                                             const ObjCEncOptions Options,
@@ -7397,6 +7431,15 @@
         S += '@';
         return;
       }
+      // If the encoded string for the class includes template names, just emit
+      // "^v" for pointers to the class.
+      if (getLangOpts().CPlusPlus &&
+          (!getLangOpts().EncodeCXXClassTemplateSpec &&
+           hasTemplateSpecializationInEncodedString(
+               RTy, Options.ExpandPointedToStructures()))) {
+        S += "^v";
+        return;
+      }
       // fall through...
     }
     S += '^';
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -5778,6 +5778,12 @@
   if (TC.IsEncodeExtendedBlockSignatureDefault())
     CmdArgs.push_back("-fencode-extended-block-signature");
 
+  if (types::isObjC(Input.getType()) &&
+      Args.hasFlag(options::OPT_fobjc_encode_cxx_class_template_spec,
+                   options::OPT_fno_objc_encode_cxx_class_template_spec,
+                   !Triple.isOSDarwin()))
+    CmdArgs.push_back("-fobjc-encode-cxx-class-template-spec");
+
   if (Args.hasFlag(options::OPT_fcoroutines_ts, options::OPT_fno_coroutines_ts,
                    false) &&
       types::isCXX(InputType)) {
diff --git a/clang/test/CodeGenObjCXX/encode.mm b/clang/test/CodeGenObjCXX/encode.mm
--- a/clang/test/CodeGenObjCXX/encode.mm
+++ b/clang/test/CodeGenObjCXX/encode.mm
@@ -1,5 +1,6 @@
-// RUN: %clang_cc1 -Wno-objc-root-class -std=gnu++98 %s -triple=x86_64-apple-darwin10 -emit-llvm -o - | FileCheck --check-prefixes CHECK,CHECKCXX98 %s
-// RUN: %clang_cc1 -Wno-objc-root-class -std=gnu++20 %s -triple=x86_64-apple-darwin10 -emit-llvm -o - | FileCheck --check-prefixes CHECK,CHECKCXX20 %s
+// RUN: %clang_cc1 -Wno-objc-root-class -std=gnu++98 %s -triple=x86_64-apple-darwin10 -emit-llvm -o - | FileCheck --check-prefixes CHECK,CHECKCXX98,CHECK-NO-TEMP-SPEC %s
+// RUN: %clang_cc1 -Wno-objc-root-class -std=gnu++20 %s -triple=x86_64-apple-darwin10 -emit-llvm -o - | FileCheck --check-prefixes CHECK,CHECKCXX20,CHECK-NO-TEMP-SPEC %s
+// RUN: %clang_cc1 -Wno-objc-root-class -std=gnu++20 %s -triple=x86_64-apple-darwin10 -fobjc-encode-cxx-class-template-spec -emit-llvm -o - | FileCheck --check-prefixes CHECK,CHECKCXX20,CHECK-TEMP-SPEC %s
 
 // CHECK: v17@0:8{vector<float, float, float>=}16
 // CHECK: {vector<float, float, float>=}
@@ -260,3 +261,63 @@
   extern const char x[] = @encode(I);
 }
 #endif
+
+namespace test_cxx_template_specialization {
+template <class T>
+struct B0 {
+  T a;
+};
+struct D0 : B0<int> {};
+struct D1 : D0 {};
+struct D2 : virtual B0<int> {};
+struct S0 {
+  B0<int> a;
+};
+struct S1 {
+  B0<int> *a;
+};
+struct S2 {
+  S1 *a;
+};
+template <class T>
+union U0 {
+  T a;
+};
+typedef B0<int> TD0;
+typedef B0<int> *Array0[4];
+
+// CHECK: @[[STR22:.*]] = {{.*}} [12 x i8] c"{B0<int>=i}\00"
+// CHECK: @_ZN32test_cxx_template_specialization2b0E = {{.*}} ([12 x i8], [12 x i8]* @[[STR22]], i32 0, i32 0)
+// CHECK-NO-TEMP-SPEC: @[[STR23:.*]] = {{.*}} [3 x i8] c"^v\00"
+// CHECK-NO-TEMP-SPEC: @_ZN32test_cxx_template_specialization3b01E = {{.*}} ([3 x i8], [3 x i8]* @[[STR23]], i32 0, i32 0)
+// CHECK-TEMP-SPEC: @[[STR23:.*]] = {{.*}} [13 x i8] c"^{B0<int>=i}\00"
+// CHECK-TEMP-SPEC: @_ZN32test_cxx_template_specialization3b01E = {{.*}} ([13 x i8], [13 x i8]* @[[STR23]], i32 0, i32 0)
+// CHECK-NO-TEMP-SPEC: @_ZN32test_cxx_template_specialization3b02E = {{.*}} ([3 x i8], [3 x i8]* @[[STR23]], i32 0, i32 0)
+// CHECK-NO-TEMP-SPEC: @_ZN32test_cxx_template_specialization2d0E = {{.*}} ([3 x i8], [3 x i8]* @[[STR23]], i32 0, i32 0)
+// CHECK-NO-TEMP-SPEC: @_ZN32test_cxx_template_specialization2d1E = {{.*}} ([3 x i8], [3 x i8]* @[[STR23]], i32 0, i32 0)
+// CHECK-NO-TEMP-SPEC: @_ZN32test_cxx_template_specialization2d2E = {{.*}} ([3 x i8], [3 x i8]* @[[STR23]], i32 0, i32 0)
+// CHECK: @[[STR24:.*]] = {{.*}} [7 x i8] c"^^{D2}\00"
+// CHECK: @_ZN32test_cxx_template_specialization3d21E = {{.*}} ([7 x i8], [7 x i8]* @[[STR24]], i32 0, i32 0)
+// CHECK-NO-TEMP-SPEC: @_ZN32test_cxx_template_specialization2s0E = {{.*}} ([3 x i8], [3 x i8]* @[[STR23]], i32 0, i32 0)
+// CHECK-NO-TEMP-SPEC: @_ZN32test_cxx_template_specialization2s1E = {{.*}} ([3 x i8], [3 x i8]* @[[STR23]], i32 0, i32 0)
+// CHECK: @[[STR25:.*]] = {{.*}} [12 x i8] c"^{S2=^{S1}}\00"
+// CHECK: @_ZN32test_cxx_template_specialization2s2E = {{.*}} ([12 x i8], [12 x i8]* @[[STR25]], i32 0, i32 0)
+// CHECK-NO-TEMP-SPEC: @_ZN32test_cxx_template_specialization2u0E = {{.*}} ([3 x i8], [3 x i8]* @[[STR23]], i32 0, i32 0)
+// CHECK-NO-TEMP-SPEC: @_ZN32test_cxx_template_specialization3td0E = {{.*}} ([3 x i8], [3 x i8]* @[[STR23]], i32 0, i32 0)
+// CHECK-NO-TEMP-SPEC: @[[STR26:.*]] = {{.*}} [6 x i8] c"[4^v]\00"
+// CHECK-NO-TEMP-SPEC: @_ZN32test_cxx_template_specialization2a0E = {{.*}} ([6 x i8], [6 x i8]* @[[STR26]], i32 0, i32 0)
+
+const char *b0 = @encode(B0<int>);
+const char *b01 = @encode(B0<int> *);
+const char *b02 = @encode(B0<int> &);
+const char *d0 = @encode(D0 *);
+const char *d1 = @encode(D1 *);
+const char *d2 = @encode(D2 *);
+const char *d21 = @encode(D2 **);
+const char *s0 = @encode(S0 *);
+const char *s1 = @encode(S1 *);
+const char *s2 = @encode(S2 *);
+const char *u0 = @encode(U0<int> *);
+const char *td0 = @encode(TD0 *);
+const char *a0 = @encode(Array0);
+}
diff --git a/clang/test/Driver/objc-encode-cxx-class-template-spec.m b/clang/test/Driver/objc-encode-cxx-class-template-spec.m
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/objc-encode-cxx-class-template-spec.m
@@ -0,0 +1,7 @@
+// RUN: %clang -target arm64-apple-ios11 -### %s -o - 2>&1 | FileCheck -check-prefix=DISABLE-ENC %s
+// RUN: %clang -target arm64-apple-ios11 -fobjc-encode-cxx-class-template-spec -### %s -o - 2>&1 | FileCheck -check-prefix=ENABLE-ENC %s
+// RUN: %clang -target x86_64-linux-gnu -fobjc-runtime=gnustep -### %s -o - 2>&1 | FileCheck -check-prefix=ENABLE-ENC %s
+// RUN: %clang -target x86_64-linux-gnu -fobjc-runtime=gnustep -fno-objc-encode-cxx-class-template-spec -### %s -o - 2>&1 |  FileCheck -check-prefix=DISABLE-ENC %s
+
+// DISABLE-ENC-NOT: -fobjc-encode-cxx-class-template-spec
+// ENABLE-ENC: -fobjc-encode-cxx-class-template-spec