diff --git a/src/services/codefixes/helpers.ts b/src/services/codefixes/helpers.ts
index 4564a571b1f43..21981c8df5f40 100644
--- a/src/services/codefixes/helpers.ts
+++ b/src/services/codefixes/helpers.ts
@@ -37,6 +37,12 @@ namespace ts.codefix {
 
     type AddNode = PropertyDeclaration | GetAccessorDeclaration | SetAccessorDeclaration | MethodDeclaration | FunctionExpression | ArrowFunction;
 
+    export const enum PreserveOptionalFlags {
+        Method  = 1 << 0,
+        Property = 1 << 1,
+        All     = Method | Property
+    }
+
     /**
      * `addClassElement` will not be called if we can't figure out a representation for `symbol` in `enclosingDeclaration`.
      * @param body If defined, this will be the body of the member node passed to `addClassElement`. Otherwise, the body will default to a stub.
@@ -50,6 +56,7 @@ namespace ts.codefix {
         importAdder: ImportAdder | undefined,
         addClassElement: (node: AddNode) => void,
         body: Block | undefined,
+        preserveOptional = PreserveOptionalFlags.All,
         isAmbient = false,
     ): void {
         const declarations = symbol.getDeclarations();
@@ -83,7 +90,7 @@ namespace ts.codefix {
                     /*decorators*/ undefined,
                     modifiers,
                     name,
-                    optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined,
+                    optional && (preserveOptional & PreserveOptionalFlags.Property) ? factory.createToken(SyntaxKind.QuestionToken) : undefined,
                     typeNode,
                     /*initializer*/ undefined));
                 break;
@@ -158,14 +165,14 @@ namespace ts.codefix {
                     }
                     else {
                         Debug.assert(declarations.length === signatures.length, "Declarations and signatures should match count");
-                        addClassElement(createMethodImplementingSignatures(checker, context, enclosingDeclaration, signatures, name, optional, modifiers, quotePreference, body));
+                        addClassElement(createMethodImplementingSignatures(checker, context, enclosingDeclaration, signatures, name, optional && !!(preserveOptional & PreserveOptionalFlags.Method), modifiers, quotePreference, body));
                     }
                 }
                 break;
         }
 
         function outputMethod(quotePreference: QuotePreference, signature: Signature, modifiers: NodeArray<Modifier> | undefined, name: PropertyName, body?: Block): void {
-            const method = createSignatureDeclarationFromSignature(SyntaxKind.MethodDeclaration, context, quotePreference, signature, body, name, modifiers, optional, enclosingDeclaration, importAdder);
+            const method = createSignatureDeclarationFromSignature(SyntaxKind.MethodDeclaration, context, quotePreference, signature, body, name, modifiers, optional && !!(preserveOptional & PreserveOptionalFlags.Method), enclosingDeclaration, importAdder);
             if (method) addClassElement(method);
         }
     }
diff --git a/src/services/completions.ts b/src/services/completions.ts
index d8b774a9404ba..7035722b3ec83 100644
--- a/src/services/completions.ts
+++ b/src/services/completions.ts
@@ -895,7 +895,7 @@ namespace ts.Completions {
             node => {
                 let requiredModifiers = ModifierFlags.None;
                 if (isAbstract) {
-                        requiredModifiers |= ModifierFlags.Abstract;
+                    requiredModifiers |= ModifierFlags.Abstract;
                 }
                 if (isClassElement(node)
                     && checker.getMemberOverrideModifierStatus(classLikeDeclaration, node) === MemberOverrideStatus.NeedsOverride) {
@@ -919,6 +919,7 @@ namespace ts.Completions {
                 completionNodes.push(node);
             },
             body,
+            codefix.PreserveOptionalFlags.Property,
             isAbstract);
 
         if (completionNodes.length) {
@@ -3888,5 +3889,6 @@ namespace ts.Completions {
         }
         return charCode;
     }
+
 }
 
diff --git a/tests/cases/fourslash/completionsOverridingMethod9.ts b/tests/cases/fourslash/completionsOverridingMethod9.ts
new file mode 100644
index 0000000000000..8f9cac56feb8a
--- /dev/null
+++ b/tests/cases/fourslash/completionsOverridingMethod9.ts
@@ -0,0 +1,44 @@
+/// <reference path="fourslash.ts" />
+
+// @Filename: a.ts
+// @newline: LF
+
+////interface IFoo {
+////    a?: number;
+////    b?(x: number): void;
+////}
+////class Foo implements IFoo {
+////    /**/
+////}
+
+verify.completions({
+    marker: "",
+    isNewIdentifierLocation: true,
+    preferences: {
+        includeCompletionsWithInsertText: true,
+        includeCompletionsWithSnippetText: false,
+        includeCompletionsWithClassMemberSnippets: true,
+    },
+    includes: [
+        {
+            name: "a",
+            sortText: completion.SortText.LocationPriority,
+            replacementSpan: {
+                fileName: "",
+                pos: 0,
+                end: 0,
+            },
+            insertText: "a?: number;\n"
+        },
+        {
+            name: "b",
+            sortText: completion.SortText.LocationPriority,
+            replacementSpan: {
+                fileName: "",
+                pos: 0,
+                end: 0,
+            },
+            insertText: "b(x: number): void {\n}\n"
+        },
+    ],
+});