diff --git a/lib/AST/ASTPrinter.cpp b/lib/AST/ASTPrinter.cpp
index 814dff53e46a2..f4034cedff5fa 100644
--- a/lib/AST/ASTPrinter.cpp
+++ b/lib/AST/ASTPrinter.cpp
@@ -5158,7 +5158,11 @@ class TypePrinter : public TypeVisitor<TypePrinter> {
                           ->castTo<GenericTypeParamType>()
                           ->getIndex();
       
-      Printer << u8") \U0001F9B8";
+      // The identifier after the closing parenthesis is irrelevant and can be
+      // anything. It just needs to be there for the @_opaqueReturnTypeOf
+      // attribute to apply to, but the attribute alone references the opaque
+      // type.
+      Printer << ") __";
       printGenericArgs(T->getSubstitutions().getReplacementTypes());
       return;
     }
diff --git a/test/AutoDiff/compiler_crashers_fixed/sr12656-differentiation-opaque-result-type.swift b/test/AutoDiff/compiler_crashers_fixed/sr12656-differentiation-opaque-result-type.swift
index eb6390c5e14a7..c5c5f1324c91f 100644
--- a/test/AutoDiff/compiler_crashers_fixed/sr12656-differentiation-opaque-result-type.swift
+++ b/test/AutoDiff/compiler_crashers_fixed/sr12656-differentiation-opaque-result-type.swift
@@ -17,7 +17,7 @@ func opaqueResult(_ x: Float) -> some Differentiable { x }
 // 2.      While evaluating request ExecuteSILPipelineRequest(Run pipelines { Guaranteed Passes } on SIL for main.main)
 // 3.      While running pass #15 SILModuleTransform "Differentiation".
 // 4.      While processing // differentiability witness for opaqueResult(_:)
-// sil_differentiability_witness hidden [reverse] [parameters 0] [results 0] @$s4main12opaqueResultyQrSfF : $@convention(thin) (Float) -> @out @_opaqueReturnTypeOf("$s4main12opaqueResultyQrSfF", 0) 🦸 {
+// sil_differentiability_witness hidden [reverse] [parameters 0] [results 0] @$s4main12opaqueResultyQrSfF : $@convention(thin) (Float) -> @out @_opaqueReturnTypeOf("$s4main12opaqueResultyQrSfF", 0) __ {
 // }
 //  on SIL function "@$s4main12opaqueResultyQrSfF".
 //  for 'opaqueResult(_:)' (at swift/test/AutoDiff/compiler_crashers/sr12656-differentiation-opaque-result-type.swift:13:1)
diff --git a/test/ModuleInterface/invalid-opaque-result-types.swift b/test/ModuleInterface/invalid-opaque-result-types.swift
index 9579bf9d3c51c..fffc5dc985ade 100644
--- a/test/ModuleInterface/invalid-opaque-result-types.swift
+++ b/test/ModuleInterface/invalid-opaque-result-types.swift
@@ -9,9 +9,9 @@
 // Then, blit some invalid opaque result types into the interface
 //
 // Test that we reject broken type parameters
-// RUN: echo "public typealias SomeGenericBalderdash = @_opaqueReturnTypeOf(\"$somesuchnonsense\", 0) 🦸<InvalidParameter>" >> %t/InvalidOpaqueResultType.swiftinterface
+// RUN: echo "public typealias SomeGenericBalderdash = @_opaqueReturnTypeOf(\"$somesuchnonsense\", 0) __<InvalidParameter>" >> %t/InvalidOpaqueResultType.swiftinterface
 // Test that we reject types we cannot demangle
-// RUN: echo "public typealias SomesuchNonsense = @_opaqueReturnTypeOf(\"$somesuchnonsense\", 0) 🦸" >> %t/InvalidOpaqueResultType.swiftinterface
+// RUN: echo "public typealias SomesuchNonsense = @_opaqueReturnTypeOf(\"$somesuchnonsense\", 0) __" >> %t/InvalidOpaqueResultType.swiftinterface
 //
 // The stage is set:
 //
diff --git a/test/SILGen/opaque_result_type.swift b/test/SILGen/opaque_result_type.swift
index 3cd92fc3da94e..66656ea0e4c57 100644
--- a/test/SILGen/opaque_result_type.swift
+++ b/test/SILGen/opaque_result_type.swift
@@ -167,7 +167,7 @@ public class D {
     }()
 }
 
-// CHECK-LABEL: sil [ossa] @$s18opaque_result_type10tupleAsAnyQryF : $@convention(thin) () -> @out @_opaqueReturnTypeOf("$s18opaque_result_type10tupleAsAnyQryF", 0) 🦸 {
+// CHECK-LABEL: sil [ossa] @$s18opaque_result_type10tupleAsAnyQryF : $@convention(thin) () -> @out @_opaqueReturnTypeOf("$s18opaque_result_type10tupleAsAnyQryF", 0) __ {
 public func tupleAsAny() -> some Any {
 // CHECK:      bb0(%0 : $*()):
 // CHECK-NEXT:   %1 = tuple ()
diff --git a/test/SILGen/opaque_result_type_class_property.swift b/test/SILGen/opaque_result_type_class_property.swift
index ea002a0d524e6..042f1b60c111e 100644
--- a/test/SILGen/opaque_result_type_class_property.swift
+++ b/test/SILGen/opaque_result_type_class_property.swift
@@ -7,8 +7,8 @@ public class HasProperty {
   public var foo: some V = E()
 }
 
-// CHECK-LABEL: sil shared [thunk] [ossa] @$s33opaque_result_type_class_property11HasPropertyC3fooQrvpACTK : $@convention(thin) (@in_guaranteed HasProperty) -> @out @_opaqueReturnTypeOf("$s33opaque_result_type_class_property11HasPropertyC3fooQrvp", 0) 🦸 {
+// CHECK-LABEL: sil shared [thunk] [ossa] @$s33opaque_result_type_class_property11HasPropertyC3fooQrvpACTK : $@convention(thin) (@in_guaranteed HasProperty) -> @out @_opaqueReturnTypeOf("$s33opaque_result_type_class_property11HasPropertyC3fooQrvp", 0) __ {
 // CHECK: bb0(%0 : $*E, %1 : $*HasProperty):
 
-// CHECK-LABEL: sil shared [thunk] [ossa] @$s33opaque_result_type_class_property11HasPropertyC3fooQrvpACTk : $@convention(thin) (@in_guaranteed @_opaqueReturnTypeOf("$s33opaque_result_type_class_property11HasPropertyC3fooQrvp", 0) 🦸, @in_guaranteed HasProperty) -> () {
+// CHECK-LABEL: sil shared [thunk] [ossa] @$s33opaque_result_type_class_property11HasPropertyC3fooQrvpACTk : $@convention(thin) (@in_guaranteed @_opaqueReturnTypeOf("$s33opaque_result_type_class_property11HasPropertyC3fooQrvp", 0) __, @in_guaranteed HasProperty) -> () {
 // CHECK: bb0(%0 : $*E, %1 : $*HasProperty):
diff --git a/test/SILGen/opaque_result_type_fragile.swift b/test/SILGen/opaque_result_type_fragile.swift
index 51de38d39d45a..782d88967a088 100644
--- a/test/SILGen/opaque_result_type_fragile.swift
+++ b/test/SILGen/opaque_result_type_fragile.swift
@@ -13,10 +13,10 @@ public func testInternalView() {
   // CHECK: function_ref @$s32opaque_result_type_fragile_other4ViewPAAE11passThroughQryF : $@convention(method) <τ_0_0 where τ_0_0 : View> (@in_guaranteed τ_0_0) -> @out τ_0_0
   _ = v.passThrough()
 
-  // CHECK: function_ref @$s32opaque_result_type_fragile_other4ViewPAAE016wrapWithInternalF0QryF : $@convention(method) <τ_0_0 where τ_0_0 : View> (@in_guaranteed τ_0_0) -> @out @_opaqueReturnTypeOf("$s32opaque_result_type_fragile_other4ViewPAAE016wrapWithInternalF0QryF", 0) 🦸<τ_0_0>
+  // CHECK: function_ref @$s32opaque_result_type_fragile_other4ViewPAAE016wrapWithInternalF0QryF : $@convention(method) <τ_0_0 where τ_0_0 : View> (@in_guaranteed τ_0_0) -> @out @_opaqueReturnTypeOf("$s32opaque_result_type_fragile_other4ViewPAAE016wrapWithInternalF0QryF", 0) __<τ_0_0>
   _ = v.wrapWithInternalView()
 
-  // CHECK: function_ref @$s32opaque_result_type_fragile_other4ViewPAAE023wrapWithInternalGenericF0QryF : $@convention(method) <τ_0_0 where τ_0_0 : View> (@in_guaranteed τ_0_0) -> @out @_opaqueReturnTypeOf("$s32opaque_result_type_fragile_other4ViewPAAE023wrapWithInternalGenericF0QryF", 0) 🦸<τ_0_0>
+  // CHECK: function_ref @$s32opaque_result_type_fragile_other4ViewPAAE023wrapWithInternalGenericF0QryF : $@convention(method) <τ_0_0 where τ_0_0 : View> (@in_guaranteed τ_0_0) -> @out @_opaqueReturnTypeOf("$s32opaque_result_type_fragile_other4ViewPAAE023wrapWithInternalGenericF0QryF", 0) __<τ_0_0>
   _ = v.wrapWithInternalGenericView()
 
   // CHECK: function_ref @$s32opaque_result_type_fragile_other4ViewPAAE014wrapWithPublicF0QryF : $@convention(method) <τ_0_0 where τ_0_0 : View> (@in_guaranteed τ_0_0) -> @out PublicView
@@ -32,10 +32,10 @@ public func testPublicView() {
   // CHECK: function_ref @$s32opaque_result_type_fragile_other4ViewPAAE11passThroughQryF : $@convention(method) <τ_0_0 where τ_0_0 : View> (@in_guaranteed τ_0_0) -> @out τ_0_0
   _ = v.passThrough()
 
-  // CHECK: function_ref @$s32opaque_result_type_fragile_other4ViewPAAE016wrapWithInternalF0QryF : $@convention(method) <τ_0_0 where τ_0_0 : View> (@in_guaranteed τ_0_0) -> @out @_opaqueReturnTypeOf("$s32opaque_result_type_fragile_other4ViewPAAE016wrapWithInternalF0QryF", 0) 🦸<τ_0_0>
+  // CHECK: function_ref @$s32opaque_result_type_fragile_other4ViewPAAE016wrapWithInternalF0QryF : $@convention(method) <τ_0_0 where τ_0_0 : View> (@in_guaranteed τ_0_0) -> @out @_opaqueReturnTypeOf("$s32opaque_result_type_fragile_other4ViewPAAE016wrapWithInternalF0QryF", 0) __<τ_0_0>
   _ = v.wrapWithInternalView()
 
-  // CHECK: function_ref @$s32opaque_result_type_fragile_other4ViewPAAE023wrapWithInternalGenericF0QryF : $@convention(method) <τ_0_0 where τ_0_0 : View> (@in_guaranteed τ_0_0) -> @out @_opaqueReturnTypeOf("$s32opaque_result_type_fragile_other4ViewPAAE023wrapWithInternalGenericF0QryF", 0) 🦸<τ_0_0>
+  // CHECK: function_ref @$s32opaque_result_type_fragile_other4ViewPAAE023wrapWithInternalGenericF0QryF : $@convention(method) <τ_0_0 where τ_0_0 : View> (@in_guaranteed τ_0_0) -> @out @_opaqueReturnTypeOf("$s32opaque_result_type_fragile_other4ViewPAAE023wrapWithInternalGenericF0QryF", 0) __<τ_0_0>
   _ = v.wrapWithInternalGenericView()
 
   // CHECK: function_ref @$s32opaque_result_type_fragile_other4ViewPAAE014wrapWithPublicF0QryF : $@convention(method) <τ_0_0 where τ_0_0 : View> (@in_guaranteed τ_0_0) -> @out PublicView
diff --git a/test/SILGen/opaque_result_type_private.swift b/test/SILGen/opaque_result_type_private.swift
index 25cff253f4d59..4004b41075071 100644
--- a/test/SILGen/opaque_result_type_private.swift
+++ b/test/SILGen/opaque_result_type_private.swift
@@ -21,12 +21,12 @@ _ = returnLocalOpaque()
 
 fileprivate class PrivateClass {}
 
-// CHECK-LABEL: sil hidden [ossa] @$s26opaque_result_type_private19returnPrivateOpaqueQryF : $@convention(thin) () -> @out @_opaqueReturnTypeOf("$s26opaque_result_type_private19returnPrivateOpaqueQryF", 0) 🦸
+// CHECK-LABEL: sil hidden [ossa] @$s26opaque_result_type_private19returnPrivateOpaqueQryF : $@convention(thin) () -> @out @_opaqueReturnTypeOf("$s26opaque_result_type_private19returnPrivateOpaqueQryF", 0) __
 func returnPrivateOpaque() -> some Any {
   return PrivateClass()
 }
 
-// CHECK-LABEL: sil hidden [ossa] @$s26opaque_result_type_private17returnLocalOpaqueQryF : $@convention(thin) () -> @out @_opaqueReturnTypeOf("$s26opaque_result_type_private17returnLocalOpaqueQryF", 0) 🦸
+// CHECK-LABEL: sil hidden [ossa] @$s26opaque_result_type_private17returnLocalOpaqueQryF : $@convention(thin) () -> @out @_opaqueReturnTypeOf("$s26opaque_result_type_private17returnLocalOpaqueQryF", 0) __
 func returnLocalOpaque() -> some Any {
   class LocalClass {}
 
diff --git a/test/SILOptimizer/specialize_opaque_type_archetypes.swift b/test/SILOptimizer/specialize_opaque_type_archetypes.swift
index c27966dd7f2d3..1a371d47c0481 100644
--- a/test/SILOptimizer/specialize_opaque_type_archetypes.swift
+++ b/test/SILOptimizer/specialize_opaque_type_archetypes.swift
@@ -541,28 +541,28 @@ public func testThinToThick() {
 // CHECK-LABEL: sil @$s1A19rdar56410009_normalyyF
 public func rdar56410009_normal() {
   // CHECK: [[EXTERNAL_RESILIENT_WRAPPER:%.+]] = function_ref @$s9External224externalResilientWrapperyQrxAA10ExternalP2RzlF
-  // CHECK: = apply [[EXTERNAL_RESILIENT_WRAPPER]]<@_opaqueReturnTypeOf("$s9External217externalResilientQryF", 0) 🦸>({{%.+}}, {{%.+}}) : $@convention(thin) <τ_0_0 where τ_0_0 : ExternalP2> (@in_guaranteed τ_0_0) -> @out @_opaqueReturnTypeOf("$s9External224externalResilientWrapperyQrxAA10ExternalP2RzlF", 0) 🦸<τ_0_0>
+  // CHECK: = apply [[EXTERNAL_RESILIENT_WRAPPER]]<@_opaqueReturnTypeOf("$s9External217externalResilientQryF", 0) __>({{%.+}}, {{%.+}}) : $@convention(thin) <τ_0_0 where τ_0_0 : ExternalP2> (@in_guaranteed τ_0_0) -> @out @_opaqueReturnTypeOf("$s9External224externalResilientWrapperyQrxAA10ExternalP2RzlF", 0) __<τ_0_0>
   _ = externalResilientWrapper(externalResilient())
 } // CHECK: end sil function '$s1A19rdar56410009_normalyyF'
 
 // CHECK-LABEL: sil @$s1A25rdar56410009_inlinedInneryyF
 public func rdar56410009_inlinedInner() {
   // CHECK: [[EXTERNAL_RESILIENT_WRAPPER:%.+]] = function_ref @$s9External224externalResilientWrapperyQrxAA10ExternalP2RzlF
-  // CHECK: = apply [[EXTERNAL_RESILIENT_WRAPPER]]<Int64>({{%.+}}, {{%.+}}) : $@convention(thin) <τ_0_0 where τ_0_0 : ExternalP2> (@in_guaranteed τ_0_0) -> @out @_opaqueReturnTypeOf("$s9External224externalResilientWrapperyQrxAA10ExternalP2RzlF", 0) 🦸<τ_0_0>
+  // CHECK: = apply [[EXTERNAL_RESILIENT_WRAPPER]]<Int64>({{%.+}}, {{%.+}}) : $@convention(thin) <τ_0_0 where τ_0_0 : ExternalP2> (@in_guaranteed τ_0_0) -> @out @_opaqueReturnTypeOf("$s9External224externalResilientWrapperyQrxAA10ExternalP2RzlF", 0) __<τ_0_0>
   _ = externalResilientWrapper(inlinableExternalResilient())
 } // CHECK: end sil function '$s1A25rdar56410009_inlinedInneryyF'
 
 // CHECK-LABEL: sil @$s1A25rdar56410009_inlinedOuteryyF
 public func rdar56410009_inlinedOuter() {
   // CHECK: [[INLINABLE_EXTERNAL_RESILIENT_WRAPPER:%.+]] = function_ref @$s9External233inlinableExternalResilientWrapperyQrxAA0C2P2RzlFAA08externalD0QryFQOyQo__Tg5
-  // CHECK: = apply [[INLINABLE_EXTERNAL_RESILIENT_WRAPPER]]({{%.+}}, {{%.+}}) : $@convention(thin) (@in_guaranteed @_opaqueReturnTypeOf("$s9External217externalResilientQryF", 0) 🦸) -> @out WrapperP2<@_opaqueReturnTypeOf("$s9External217externalResilientQryF"
+  // CHECK: = apply [[INLINABLE_EXTERNAL_RESILIENT_WRAPPER]]({{%.+}}, {{%.+}}) : $@convention(thin) (@in_guaranteed @_opaqueReturnTypeOf("$s9External217externalResilientQryF", 0) __) -> @out WrapperP2<@_opaqueReturnTypeOf("$s9External217externalResilientQryF"
   _ = inlinableExternalResilientWrapper(externalResilient())
 } // CHECK: end sil function '$s1A25rdar56410009_inlinedOuteryyF'
 
 // Specialized from above
 // CHECK-LABEL: sil shared [noinline] @$s9External233inlinableExternalResilientWrapperyQrxAA0C2P2RzlFAA08externalD0QryFQOyQo__Tg5
 // CHECK: [[WRAPPER_INIT:%.+]] = function_ref @$s9External29WrapperP2VyACyxGxcfC
-// CHECK: = apply [[WRAPPER_INIT]]<@_opaqueReturnTypeOf("$s9External217externalResilientQryF", 0) 🦸>({{%.+}}, {{%.+}}, {{%.+}}) : $@convention(method) <τ_0_0 where τ_0_0 : ExternalP2> (@in τ_0_0, @thin WrapperP2<τ_0_0>.Type) -> @out WrapperP2<τ_0_0>
+// CHECK: = apply [[WRAPPER_INIT]]<@_opaqueReturnTypeOf("$s9External217externalResilientQryF", 0) __>({{%.+}}, {{%.+}}, {{%.+}}) : $@convention(method) <τ_0_0 where τ_0_0 : ExternalP2> (@in τ_0_0, @thin WrapperP2<τ_0_0>.Type) -> @out WrapperP2<τ_0_0>
 // CHECK: end sil function '$s9External233inlinableExternalResilientWrapperyQrxAA0C2P2RzlFAA08externalD0QryFQOyQo__Tg5'
 
 // Specialized from below