diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 70bd2c29b7a..ba62eb16d39 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -968,6 +968,7 @@ namespace ts {
             name: "useDefineForClassFields",
             type: "boolean",
             affectsSemanticDiagnostics: true,
+            affectsEmit: true,
             category: Diagnostics.Advanced_Options,
             description: Diagnostics.Emit_class_fields_with_Define_instead_of_Set,
         },
diff --git a/src/testRunner/unittests/tscWatch/programUpdates.ts b/src/testRunner/unittests/tscWatch/programUpdates.ts
index ede0927aa19..82d61ae2557 100644
--- a/src/testRunner/unittests/tscWatch/programUpdates.ts
+++ b/src/testRunner/unittests/tscWatch/programUpdates.ts
@@ -1121,6 +1121,31 @@ foo().hello`
             ]
         });
 
+        verifyTscWatch({
+            scenario,
+            subScenario: "updates diagnostics and emit when useDefineForClassFields changes",
+            commandLineArgs: ["-w"],
+            sys: () => {
+                const aFile: File = {
+                    path: `/a.ts`,
+                    content: `class C { get prop() { return 1; } }
+class D extends C { prop = 1; }`
+                };
+                const config: File = {
+                    path: `/tsconfig.json`,
+                    content: JSON.stringify({ compilerOptions: { target: "es6" } })
+                };
+                return createWatchedSystem([aFile, config, libFile]);
+            },
+            changes: [
+                sys => {
+                    sys.writeFile(`/tsconfig.json`, JSON.stringify({ compilerOptions: { target: "es6", useDefineForClassFields: true } }));
+                    sys.runQueuedTimeoutCallbacks();
+                    return "Enable useDefineForClassFields";
+                },
+            ]
+        });
+
         verifyTscWatch({
             scenario,
             subScenario: "updates errors and emit when importsNotUsedAsValues changes",
diff --git a/tests/baselines/reference/tscWatch/programUpdates/updates-diagnostics-and-emit-when-useDefineForClassFields-changes.js b/tests/baselines/reference/tscWatch/programUpdates/updates-diagnostics-and-emit-when-useDefineForClassFields-changes.js
new file mode 100644
index 00000000000..f5c4d978b17
--- /dev/null
+++ b/tests/baselines/reference/tscWatch/programUpdates/updates-diagnostics-and-emit-when-useDefineForClassFields-changes.js
@@ -0,0 +1,128 @@
+/a/lib/tsc.js -w
+//// [/a.ts]
+class C { get prop() { return 1; } }
+class D extends C { prop = 1; }
+
+//// [/tsconfig.json]
+{"compilerOptions":{"target":"es6"}}
+
+//// [/a/lib/lib.d.ts]
+/// <reference no-default-lib="true"/>
+interface Boolean {}
+interface Function {}
+interface CallableFunction {}
+interface NewableFunction {}
+interface IArguments {}
+interface Number { toExponential: any; }
+interface Object {}
+interface RegExp {}
+interface String { charAt: any; }
+interface Array<T> { length: number; [n: number]: T; }
+
+//// [/a.js]
+class C {
+    get prop() { return 1; }
+}
+class D extends C {
+    constructor() {
+        super(...arguments);
+        this.prop = 1;
+    }
+}
+
+
+
+Output::
+>> Screen clear
+12:00:13 AM - Starting compilation in watch mode...
+
+
+
+12:00:16 AM - Found 0 errors. Watching for file changes.
+
+
+Program root files: ["/a.ts","/a/lib/lib.d.ts"]
+Program options: {"target":2,"watch":true,"configFilePath":"/tsconfig.json"}
+Program files::
+/a.ts
+/a/lib/lib.d.ts
+
+Semantic diagnostics in builder refreshed for::
+/a.ts
+/a/lib/lib.d.ts
+
+WatchedFiles::
+/tsconfig.json:
+  {"pollingInterval":250}
+/a.ts:
+  {"pollingInterval":250}
+/a/lib/lib.d.ts:
+  {"pollingInterval":250}
+
+FsWatches::
+
+FsWatchesRecursive::
+/:
+  {"fallbackPollingInterval":500,"fallbackOptions":{"watchFile":"PriorityPollingInterval"}}
+
+exitCode:: ExitStatus.undefined
+
+Change:: Enable useDefineForClassFields
+
+//// [/tsconfig.json]
+{"compilerOptions":{"target":"es6","useDefineForClassFields":true}}
+
+//// [/a.js]
+class C {
+    get prop() { return 1; }
+}
+class D extends C {
+    constructor() {
+        super(...arguments);
+        Object.defineProperty(this, "prop", {
+            enumerable: true,
+            configurable: true,
+            writable: true,
+            value: 1
+        });
+    }
+}
+
+
+
+Output::
+>> Screen clear
+12:00:20 AM - File change detected. Starting incremental compilation...
+
+
+a.ts(2,21): error TS2610: 'prop' is defined as an accessor in class 'C', but is overridden here in 'D' as an instance property.
+
+
+12:00:24 AM - Found 1 error. Watching for file changes.
+
+
+Program root files: ["/a.ts","/a/lib/lib.d.ts"]
+Program options: {"target":2,"useDefineForClassFields":true,"watch":true,"configFilePath":"/tsconfig.json"}
+Program files::
+/a.ts
+/a/lib/lib.d.ts
+
+Semantic diagnostics in builder refreshed for::
+/a.ts
+/a/lib/lib.d.ts
+
+WatchedFiles::
+/tsconfig.json:
+  {"pollingInterval":250}
+/a.ts:
+  {"pollingInterval":250}
+/a/lib/lib.d.ts:
+  {"pollingInterval":250}
+
+FsWatches::
+
+FsWatchesRecursive::
+/:
+  {"fallbackPollingInterval":500,"fallbackOptions":{"watchFile":"PriorityPollingInterval"}}
+
+exitCode:: ExitStatus.undefined