diff --git a/src/compiler/transformers/classFields.ts b/src/compiler/transformers/classFields.ts
index 3bd3d1b1cbb..e898f9199f7 100644
--- a/src/compiler/transformers/classFields.ts
+++ b/src/compiler/transformers/classFields.ts
@@ -1335,6 +1335,11 @@ namespace ts {
                 setSourceMapRange(statement, moveRangePastModifiers(property));
                 setCommentRange(statement, property);
                 setOriginalNode(statement, property);
+                // `setOriginalNode` *copies* the `emitNode` from `property`, so now both
+                // `statement` and `expression` have a copy of the synthesized comments.
+                // Drop the comments from expression to avoid printing them twice.
+                setSyntheticLeadingComments(expression, undefined);
+                setSyntheticTrailingComments(expression, undefined);
                 statements.push(statement);
             }
         }
diff --git a/src/testRunner/unittests/transform.ts b/src/testRunner/unittests/transform.ts
index 476dc6540d5..256a1db2e30 100644
--- a/src/testRunner/unittests/transform.ts
+++ b/src/testRunner/unittests/transform.ts
@@ -599,6 +599,63 @@ module MyModule {
         }, exports => {
             assert.equal(exports.stringLength, 5);
         });
+
+        function addStaticFieldWithComment(context: TransformationContext) {
+            return (sourceFile: SourceFile): SourceFile => {
+                return visitNode(sourceFile, rootTransform, isSourceFile);
+            };
+            function rootTransform<T extends Node>(node: T): Node {
+                if (isClassLike(node)) {
+                    const newMembers = [factory.createPropertyDeclaration(/* decorators */ undefined, [factory.createModifier(SyntaxKind.StaticKeyword)], "newField", /* questionOrExclamationToken */ undefined, /* type */ undefined, factory.createStringLiteral("x"))];
+                    setSyntheticLeadingComments(newMembers[0], [{ kind: SyntaxKind.MultiLineCommentTrivia, text: "comment", pos: -1, end: -1, hasTrailingNewLine: true }]);
+                    return isClassDeclaration(node) ?
+                        factory.updateClassDeclaration(
+                            node, node.decorators,
+                            /* modifierFlags */ undefined, node.name,
+                            node.typeParameters, node.heritageClauses,
+                            newMembers) :
+                        factory.updateClassExpression(
+                            node, node.decorators,
+                            /* modifierFlags */ undefined, node.name,
+                            node.typeParameters, node.heritageClauses,
+                            newMembers);
+                }
+                return visitEachChild(node, rootTransform, context);
+            }
+        }
+
+        testBaseline("transformSyntheticCommentOnStaticFieldInClassDeclaration", () => {
+            return transpileModule(`
+declare const Decorator: any;
+@Decorator
+class MyClass {
+}
+`, {
+                transformers: {
+                    before: [addStaticFieldWithComment],
+                },
+                compilerOptions: {
+                    target: ScriptTarget.ES2015,
+                    newLine: NewLineKind.CarriageReturnLineFeed,
+                }
+            }).outputText;
+        });
+
+        testBaseline("transformSyntheticCommentOnStaticFieldInClassExpression", () => {
+            return transpileModule(`
+const MyClass = class {
+};
+`, {
+                transformers: {
+                    before: [addStaticFieldWithComment],
+                },
+                compilerOptions: {
+                    target: ScriptTarget.ES2015,
+                    newLine: NewLineKind.CarriageReturnLineFeed,
+                }
+            }).outputText;
+        });
+
     });
 }
 
diff --git a/tests/baselines/reference/transformApi/transformsCorrectly.transformSyntheticCommentOnStaticFieldInClassDeclaration.js b/tests/baselines/reference/transformApi/transformsCorrectly.transformSyntheticCommentOnStaticFieldInClassDeclaration.js
new file mode 100644
index 00000000000..df471270ae2
--- /dev/null
+++ b/tests/baselines/reference/transformApi/transformsCorrectly.transformSyntheticCommentOnStaticFieldInClassDeclaration.js
@@ -0,0 +1,13 @@
+var __decorate = (this && this.__decorate) || function (decorators, target, key, desc) {
+    var c = arguments.length, r = c < 3 ? target : desc === null ? desc = Object.getOwnPropertyDescriptor(target, key) : desc, d;
+    if (typeof Reflect === "object" && typeof Reflect.decorate === "function") r = Reflect.decorate(decorators, target, key, desc);
+    else for (var i = decorators.length - 1; i >= 0; i--) if (d = decorators[i]) r = (c < 3 ? d(r) : c > 3 ? d(target, key, r) : d(target, key)) || r;
+    return c > 3 && r && Object.defineProperty(target, key, r), r;
+};
+let MyClass = class MyClass {
+};
+/*comment*/
+MyClass.newField = "x";
+MyClass = __decorate([
+    Decorator
+], MyClass);
diff --git a/tests/baselines/reference/transformApi/transformsCorrectly.transformSyntheticCommentOnStaticFieldInClassExpression.js b/tests/baselines/reference/transformApi/transformsCorrectly.transformSyntheticCommentOnStaticFieldInClassExpression.js
new file mode 100644
index 00000000000..e6ca9fc6ac3
--- /dev/null
+++ b/tests/baselines/reference/transformApi/transformsCorrectly.transformSyntheticCommentOnStaticFieldInClassExpression.js
@@ -0,0 +1,6 @@
+var _a;
+const MyClass = (_a = class {
+    },
+    /*comment*/
+    _a.newField = "x",
+    _a);