diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 6b43b3802c2a4..7b9cc76b11b8c 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -12740,7 +12740,7 @@ namespace ts {
             }
 
             if (!compilerOptions.experimentalDecorators) {
-                error(node, Diagnostics.Experimental_support_for_decorators_is_a_feature_that_is_subject_to_change_in_a_future_release_Specify_experimentalDecorators_to_remove_this_warning);
+                error(node, Diagnostics.Experimental_support_for_decorators_is_a_feature_that_is_subject_to_change_in_a_future_release_Set_the_experimentalDecorators_option_to_remove_this_warning);
             }
 
             if (compilerOptions.emitDecoratorMetadata) {
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 25b86e67d34fe..1829e99eb1664 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -687,7 +687,7 @@
         "category": "Error",
         "code": 1218
     },
-    "Experimental support for decorators is a feature that is subject to change in a future release. Specify '--experimentalDecorators' to remove this warning.": {
+    "Experimental support for decorators is a feature that is subject to change in a future release. Set the 'experimentalDecorators' option to remove this warning.": {
         "category": "Error",
         "code": 1219
     },
@@ -2729,11 +2729,6 @@
         "category": "Error",
         "code": 8016
     },
-    "'decorators' can only be used in a .ts file.": {
-        "category": "Error",
-        "code": 8017
-    },
-
     "Only identifiers/qualified-names with optional type arguments are currently supported in a class 'extends' clauses.": {
         "category": "Error",
         "code": 9002
diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 7a2e65ed33bad..a51b3eed4bf49 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -1169,7 +1169,9 @@ namespace ts {
                             diagnostics.push(createDiagnosticForNode(typeAssertionExpression.type, Diagnostics.type_assertion_expressions_can_only_be_used_in_a_ts_file));
                             return true;
                         case SyntaxKind.Decorator:
-                            diagnostics.push(createDiagnosticForNode(node, Diagnostics.decorators_can_only_be_used_in_a_ts_file));
+                            if (!options.experimentalDecorators) {
+                                diagnostics.push(createDiagnosticForNode(node, Diagnostics.Experimental_support_for_decorators_is_a_feature_that_is_subject_to_change_in_a_future_release_Set_the_experimentalDecorators_option_to_remove_this_warning));
+                            }
                             return true;
                     }
 
diff --git a/tests/baselines/reference/generatorTypeCheck39.errors.txt b/tests/baselines/reference/generatorTypeCheck39.errors.txt
index ae24837f712b5..aabb5a47a355d 100644
--- a/tests/baselines/reference/generatorTypeCheck39.errors.txt
+++ b/tests/baselines/reference/generatorTypeCheck39.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck39.ts(5,16): error TS1163: A 'yield' expression is only allowed in a generator body.
-tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck39.ts(6,11): error TS1219: Experimental support for decorators is a feature that is subject to change in a future release. Specify '--experimentalDecorators' to remove this warning.
+tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck39.ts(6,11): error TS1219: Experimental support for decorators is a feature that is subject to change in a future release. Set the 'experimentalDecorators' option to remove this warning.
 tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck39.ts(7,13): error TS1163: A 'yield' expression is only allowed in a generator body.
 
 
@@ -13,7 +13,7 @@ tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck39.ts(7,13): erro
 !!! error TS1163: A 'yield' expression is only allowed in a generator body.
         class C {
               ~
-!!! error TS1219: Experimental support for decorators is a feature that is subject to change in a future release. Specify '--experimentalDecorators' to remove this warning.
+!!! error TS1219: Experimental support for decorators is a feature that is subject to change in a future release. Set the 'experimentalDecorators' option to remove this warning.
             x = yield 0;
                 ~~~~~
 !!! error TS1163: A 'yield' expression is only allowed in a generator body.
diff --git a/tests/baselines/reference/generatorTypeCheck59.errors.txt b/tests/baselines/reference/generatorTypeCheck59.errors.txt
index d817980382177..cba90154701af 100644
--- a/tests/baselines/reference/generatorTypeCheck59.errors.txt
+++ b/tests/baselines/reference/generatorTypeCheck59.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck59.ts(3,11): error TS1163: A 'yield' expression is only allowed in a generator body.
-tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck59.ts(4,9): error TS1219: Experimental support for decorators is a feature that is subject to change in a future release. Specify '--experimentalDecorators' to remove this warning.
+tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck59.ts(4,9): error TS1219: Experimental support for decorators is a feature that is subject to change in a future release. Set the 'experimentalDecorators' option to remove this warning.
 
 
 ==== tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck59.ts (2 errors) ====
@@ -10,6 +10,6 @@ tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck59.ts(4,9): error
 !!! error TS1163: A 'yield' expression is only allowed in a generator body.
             m() { }
             ~
-!!! error TS1219: Experimental support for decorators is a feature that is subject to change in a future release. Specify '--experimentalDecorators' to remove this warning.
+!!! error TS1219: Experimental support for decorators is a feature that is subject to change in a future release. Set the 'experimentalDecorators' option to remove this warning.
         };
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/generatorTypeCheck61.errors.txt b/tests/baselines/reference/generatorTypeCheck61.errors.txt
index b38e96d31ce13..ccc99f7ffbd34 100644
--- a/tests/baselines/reference/generatorTypeCheck61.errors.txt
+++ b/tests/baselines/reference/generatorTypeCheck61.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck61.ts(2,7): error TS1163: A 'yield' expression is only allowed in a generator body.
-tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck61.ts(3,11): error TS1219: Experimental support for decorators is a feature that is subject to change in a future release. Specify '--experimentalDecorators' to remove this warning.
+tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck61.ts(3,11): error TS1219: Experimental support for decorators is a feature that is subject to change in a future release. Set the 'experimentalDecorators' option to remove this warning.
 
 
 ==== tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck61.ts (2 errors) ====
@@ -9,5 +9,5 @@ tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck61.ts(3,11): erro
 !!! error TS1163: A 'yield' expression is only allowed in a generator body.
         class C {};
               ~
-!!! error TS1219: Experimental support for decorators is a feature that is subject to change in a future release. Specify '--experimentalDecorators' to remove this warning.
+!!! error TS1219: Experimental support for decorators is a feature that is subject to change in a future release. Set the 'experimentalDecorators' option to remove this warning.
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/jsFileCompilationDecoratorSyntax.errors.txt b/tests/baselines/reference/jsFileCompilationDecoratorSyntax.errors.txt
deleted file mode 100644
index a39d2e1665cf9..0000000000000
--- a/tests/baselines/reference/jsFileCompilationDecoratorSyntax.errors.txt
+++ /dev/null
@@ -1,9 +0,0 @@
-error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
-tests/cases/compiler/a.js(1,1): error TS8017: 'decorators' can only be used in a .ts file.
-
-
-!!! error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
-==== tests/cases/compiler/a.js (1 errors) ====
-    @internal class C { }
-    ~~~~~~~~~
-!!! error TS8017: 'decorators' can only be used in a .ts file.
\ No newline at end of file
diff --git a/tests/baselines/reference/jsFileCompilationDecoratorSyntax.symbols b/tests/baselines/reference/jsFileCompilationDecoratorSyntax.symbols
new file mode 100644
index 0000000000000..02973b4314766
--- /dev/null
+++ b/tests/baselines/reference/jsFileCompilationDecoratorSyntax.symbols
@@ -0,0 +1,4 @@
+=== tests/cases/compiler/a.js ===
+@internal class C { }
+>C : Symbol(C, Decl(a.js, 0, 0))
+
diff --git a/tests/baselines/reference/jsFileCompilationDecoratorSyntax.types b/tests/baselines/reference/jsFileCompilationDecoratorSyntax.types
new file mode 100644
index 0000000000000..ee1f14129d5fb
--- /dev/null
+++ b/tests/baselines/reference/jsFileCompilationDecoratorSyntax.types
@@ -0,0 +1,5 @@
+=== tests/cases/compiler/a.js ===
+@internal class C { }
+>internal : any
+>C : C
+
diff --git a/tests/cases/compiler/jsFileCompilationDecoratorSyntax.ts b/tests/cases/compiler/jsFileCompilationDecoratorSyntax.ts
index 2ef95db01fe1f..6627fb5dca036 100644
--- a/tests/cases/compiler/jsFileCompilationDecoratorSyntax.ts
+++ b/tests/cases/compiler/jsFileCompilationDecoratorSyntax.ts
@@ -1,3 +1,5 @@
 // @allowJs: true
+// @noEmit: true
+// @experimentalDecorators: true
 // @filename: a.js
-@internal class C { }
\ No newline at end of file
+@internal class C { }
diff --git a/tests/cases/fourslash/getJavaScriptSemanticDiagnostics21.ts b/tests/cases/fourslash/getJavaScriptSemanticDiagnostics21.ts
index b71677554a215..8a7120acbb371 100644
--- a/tests/cases/fourslash/getJavaScriptSemanticDiagnostics21.ts
+++ b/tests/cases/fourslash/getJavaScriptSemanticDiagnostics21.ts
@@ -1,15 +1,8 @@
 /// <reference path="fourslash.ts" />
 
 // @allowJs: true
+// @experimentalDecorators: true
 // @Filename: a.js
 //// @internal class C {}
 
-verify.getSemanticDiagnostics(`[
-  {
-    "message": "'decorators' can only be used in a .ts file.",
-    "start": 0,
-    "length": 9,
-    "category": "error",
-    "code": 8017
-  }
-]`);
\ No newline at end of file
+verify.getSemanticDiagnostics(`[]`);