diff --git a/SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyBuiltin.swift b/SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyBuiltin.swift
index 2c60d7055df90..72fd794bf2874 100644
--- a/SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyBuiltin.swift
+++ b/SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyBuiltin.swift
@@ -184,8 +184,13 @@ private func typesOfValuesAreEqual(_ lhs: Value, _ rhs: Value, in function: Func
     return nil
   }
 
-  let lhsTy = lhsExistential.metatype.type.instanceTypeOfMetatype(in: function)
-  let rhsTy = rhsExistential.metatype.type.instanceTypeOfMetatype(in: function)
+  let lhsMetatype = lhsExistential.metatype.type
+  let rhsMetatype = rhsExistential.metatype.type
+  if lhsMetatype.isDynamicSelfMetatype != rhsMetatype.isDynamicSelfMetatype {
+    return nil
+  }
+  let lhsTy = lhsMetatype.instanceTypeOfMetatype(in: function)
+  let rhsTy = rhsMetatype.instanceTypeOfMetatype(in: function)
 
   // Do we know the exact types? This is not the case e.g. if a type is passed as metatype
   // to the function.
diff --git a/SwiftCompilerSources/Sources/SIL/Type.swift b/SwiftCompilerSources/Sources/SIL/Type.swift
index c7fdca56ee76d..89dd4523db1db 100644
--- a/SwiftCompilerSources/Sources/SIL/Type.swift
+++ b/SwiftCompilerSources/Sources/SIL/Type.swift
@@ -90,6 +90,10 @@ public struct Type : CustomStringConvertible, NoReflectionChildren {
     bridged.getInstanceTypeOfMetatype(function.bridged.getFunction()).type
   }
 
+  public var isDynamicSelfMetatype: Bool {
+    bridged.isDynamicSelfMetatype()
+  }
+
   public var isCalleeConsumedFunction: Bool { bridged.isCalleeConsumedFunction() }
 
   public var isMarkedAsImmortal: Bool { bridged.isMarkedAsImmortal() }
diff --git a/include/swift/SIL/SILType.h b/include/swift/SIL/SILType.h
index 9b13df04d1416..ba179061b0d3f 100644
--- a/include/swift/SIL/SILType.h
+++ b/include/swift/SIL/SILType.h
@@ -508,6 +508,12 @@ class SILType {
     return isObject() && isClassOrClassMetatype(getASTType());
   }
 
+  bool isDynamicSelfMetatype() const {
+    auto metaType = castTo<swift::MetatypeType>();
+    Type instTy = metaType->getInstanceType();
+    return instTy->is<DynamicSelfType>();
+  }
+
   bool isFunctionTypeWithContext() const {
     if (auto *fTy = getASTType()->getAs<SILFunctionType>()) {
       return fTy->getExtInfo().hasContext();
diff --git a/test/SILOptimizer/simplify_builtin.sil b/test/SILOptimizer/simplify_builtin.sil
index 7192a1d0e0be9..2c713657a89aa 100644
--- a/test/SILOptimizer/simplify_builtin.sil
+++ b/test/SILOptimizer/simplify_builtin.sil
@@ -26,6 +26,9 @@ class C1<T> {
 class C2<T> : C1<T> {
 }
 
+class A {
+}
+
 // CHECK-LABEL: sil @constantFoldAdd
 // CHECK:         [[A:%.*]] = integer_literal $Builtin.Int64, 12
 // CHECK:         [[C:%.*]] = integer_literal $Builtin.Int1, 0
@@ -267,6 +270,34 @@ bb0:
   return %4 : $Builtin.Int1
 }
 
+// CHECK-LABEL: sil @same_metatype_dynamic_self
+// CHECK:         [[R:%.*]] = integer_literal $Builtin.Int1, -1
+// CHECK-NEXT:    return [[R]]
+// CHECK:       } // end sil function 'same_metatype_dynamic_self'
+sil @same_metatype_dynamic_self : $@convention(method) (@guaranteed A) -> Builtin.Int1 {
+bb0(%0 : $A):
+  %2 = metatype $@thick @dynamic_self A.Type
+  %3 = init_existential_metatype %2 : $@thick @dynamic_self A.Type, $@thick any Any.Type
+  %5 = metatype $@thick @dynamic_self A.Type
+  %6 = init_existential_metatype %5 : $@thick @dynamic_self A.Type, $@thick any Any.Type
+  %13 = builtin "is_same_metatype"(%3 : $@thick any Any.Type, %6 : $@thick any Any.Type) : $Builtin.Int1
+  return %13 : $Builtin.Int1
+}
+
+// CHECK-LABEL: sil @unknown_same_metatype_dynamic_self
+// CHECK:         [[R:%.*]] = builtin "is_same_metatype"
+// CHECK:         return [[R]]
+// CHECK:       } // end sil function 'unknown_same_metatype_dynamic_self'
+sil @unknown_same_metatype_dynamic_self : $@convention(method) (@guaranteed A) -> Builtin.Int1 {
+bb0(%0 : $A):
+  %2 = metatype $@thick @dynamic_self A.Type
+  %3 = init_existential_metatype %2 : $@thick @dynamic_self A.Type, $@thick any Any.Type
+  %5 = metatype $@thick A.Type
+  %6 = init_existential_metatype %5 : $@thick A.Type, $@thick any Any.Type
+  %13 = builtin "is_same_metatype"(%3 : $@thick any Any.Type, %6 : $@thick any Any.Type) : $Builtin.Int1
+  return %13 : $Builtin.Int1
+}
+
 sil_global hidden [let] @g : $Int32
 
 sil [global_init_once_fn] @side_effect_free_init : $@convention(c) () -> () {