diff --git a/dev/core/src/com/google/gwt/dev/javac/JsInteropUtil.java b/dev/core/src/com/google/gwt/dev/javac/JsInteropUtil.java
index 020ce6e..e15b624 100644
--- a/dev/core/src/com/google/gwt/dev/javac/JsInteropUtil.java
+++ b/dev/core/src/com/google/gwt/dev/javac/JsInteropUtil.java
@@ -21,6 +21,7 @@
 import com.google.gwt.dev.jjs.ast.JField;
 import com.google.gwt.dev.jjs.ast.JMember;
 import com.google.gwt.dev.jjs.ast.JMethod;
+import com.google.gwt.dev.jjs.ast.JParameter;
 import com.google.gwt.dev.jjs.ast.JPrimitiveType;
 
 import org.eclipse.jdt.internal.compiler.ast.Annotation;
@@ -68,6 +69,12 @@
     setJsInteropProperties(method, annotations, annotation, isPropertyAccessor, generateExport);
   }
 
+  public static void maybeSetJsInteropProperties(JParameter parameter,  Annotation... annotations) {
+    if (getInteropAnnotation(annotations, "JsOptional") != null) {
+      parameter.setOptional();
+    }
+  }
+
   public static void maybeSetJsInteropProperties(
       JField field, boolean generateExport, Annotation... annotations) {
     AnnotationBinding annotation = getInteropAnnotation(annotations, "JsProperty");
@@ -86,7 +93,8 @@
 
     boolean isPublicMemberForJsType = member.getEnclosingType().isJsType() && member.isPublic();
     boolean memberForNativeType = member.getEnclosingType().isJsNative();
-    if (!isPublicMemberForJsType && !memberForNativeType && memberAnnotation == null) {
+    if (memberAnnotation == null
+        && (!isPublicMemberForJsType && !memberForNativeType || member.isJsOverlay())) {
       return;
     }
 
diff --git a/dev/core/src/com/google/gwt/dev/javac/testing/impl/JavaResourceBase.java b/dev/core/src/com/google/gwt/dev/javac/testing/impl/JavaResourceBase.java
index 37d7e7a..022f114 100644
--- a/dev/core/src/com/google/gwt/dev/javac/testing/impl/JavaResourceBase.java
+++ b/dev/core/src/com/google/gwt/dev/javac/testing/impl/JavaResourceBase.java
@@ -419,6 +419,11 @@
           "package jsinterop.annotations;",
           "public @interface JsFunction {",
           "}");
+  public static final MockJavaResource JSOPTIONAL =
+      createMockJavaResource("jsinterop.annotations.JsOptional",
+          "package jsinterop.annotations;",
+          "public @interface JsOptional {",
+          "}");
   public static final MockJavaResource JSOVERLAY =
       createMockJavaResource("jsinterop.annotations.JsOverlay",
           "package jsinterop.annotations;",
@@ -433,7 +438,7 @@
         JAVASCRIPTOBJECT, LIST, LONG, MAP, NO_CLASS_DEF_FOUND_ERROR, NUMBER, OBJECT,
         RUNTIME_EXCEPTION, SERIALIZABLE, SHORT, STRING, STRING_BUILDER, SUPPRESS_WARNINGS, SYSTEM,
         THROWABLE, SPECIALIZE_METHOD, JSTYPE, JSCONSTRUCTOR, JSPACKAGE, JSPROPERTY, JSMETHOD,
-        JSIGNORE, JSFUNCTION, JSOVERLAY};
+        JSIGNORE, JSFUNCTION, JSOVERLAY, JSOPTIONAL};
   }
 
   /**
diff --git a/dev/core/src/com/google/gwt/dev/jjs/ast/JMethod.java b/dev/core/src/com/google/gwt/dev/jjs/ast/JMethod.java
index fbfbd0a..8615cae 100644
--- a/dev/core/src/com/google/gwt/dev/jjs/ast/JMethod.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/ast/JMethod.java
@@ -99,14 +99,14 @@
    * Adds a new final parameter to this method.
    */
   public JParameter createFinalParameter(SourceInfo info, String name, JType type) {
-    return createParameter(info, name, type, true, false, false);
+    return createParameter(info, name, type, true, false, false, false);
   }
 
   /**
    * Adds a new parameter to this method.
    */
   public JParameter createParameter(SourceInfo info, String name, JType type) {
-    return createParameter(info, name, type, false, false, false);
+    return createParameter(info, name, type, false, false, false, false);
   }
 
   /**
@@ -114,7 +114,7 @@
    */
   public JParameter createParameter(SourceInfo info, String name, JType type, boolean isFinal,
       boolean isVarargs) {
-    return createParameter(info, name, type, isFinal, isVarargs, false);
+    return createParameter(info, name, type, isFinal, isVarargs, false, false);
   }
 
   /**
@@ -122,22 +122,22 @@
    */
   public JParameter cloneParameter(JParameter from) {
     return createParameter(from.getSourceInfo(), from.getName(), from.getType(), from.isFinal(),
-        from.isVarargs(), from.isThis());
+        from.isVarargs(), from.isThis(), from.isOptional());
   }
 
   /**
    * Creates a parameter to hold the value of this in devirtualized methods.
    */
   public JParameter createThisParameter(SourceInfo info, JType type) {
-    return createParameter(info,  "this$static", type, true, false, true);
+    return createParameter(info,  "this$static", type, true, false, true, false);
   }
 
   private JParameter createParameter(SourceInfo info, String name, JType type,
-      boolean isFinal, boolean isVarargs, boolean isThis) {
+      boolean isFinal, boolean isVarargs, boolean isThis, boolean isOptional) {
     assert (name != null);
     assert (type != null);
 
-    JParameter parameter = new JParameter(info, name, type, isFinal, isVarargs, isThis);
+    JParameter parameter = new JParameter(info, name, type, isFinal, isVarargs, isThis, isOptional);
     addParameter(parameter);
     return parameter;
   }
diff --git a/dev/core/src/com/google/gwt/dev/jjs/ast/JParameter.java b/dev/core/src/com/google/gwt/dev/jjs/ast/JParameter.java
index 4fa7e00..ca9e7c1 100644
--- a/dev/core/src/com/google/gwt/dev/jjs/ast/JParameter.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/ast/JParameter.java
@@ -24,22 +24,32 @@
 
   private final boolean isThis;
   private final boolean isVarags;
+  private boolean isOptional;
 
   public JParameter(SourceInfo info, String name, JType type, boolean isFinal) {
-    this(info, name, type, isFinal, false, false);
+    this(info, name, type, isFinal, false, false, false);
   }
 
   JParameter(SourceInfo info, String name, JType type, boolean isFinal, boolean isVarargs,
-      boolean isThis) {
+      boolean isThis, boolean isOptional) {
     super(info, name, type, isFinal);
     this.isThis = isThis;
     this.isVarags = isVarargs;
+    this.isOptional = isOptional;
     assert !isVarargs || type.isArrayType();
   }
 
   public JParameterRef createRef(SourceInfo info) {
     return new JParameterRef(info, this);
   }
+
+  /**
+   * Returns <code>true</code> if this parameter marked as optional.
+   */
+  public boolean isOptional() {
+    return isOptional;
+  }
+
   /**
    * Returns <code>true</code> if this parameter is the this parameter of a
    * static impl method.
@@ -55,6 +65,10 @@
     return isVarags;
   }
 
+  public void setOptional() {
+    isOptional = true;
+  }
+
   @Override
   public JParameterRef makeRef(SourceInfo info) {
     return new JParameterRef(info, this);
diff --git a/dev/core/src/com/google/gwt/dev/jjs/impl/GwtAstBuilder.java b/dev/core/src/com/google/gwt/dev/jjs/impl/GwtAstBuilder.java
index dd5e9ec..6debb78 100644
--- a/dev/core/src/com/google/gwt/dev/jjs/impl/GwtAstBuilder.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/impl/GwtAstBuilder.java
@@ -4081,6 +4081,11 @@
     processSuppressedWarnings(method, x.annotations);
   }
 
+  private void processAnnotations(JParameter parameter, Annotation... annotations) {
+    JsInteropUtil.maybeSetJsInteropProperties(parameter, annotations);
+    processSuppressedWarnings(parameter, annotations);
+  }
+
   private void processSuppressedWarnings(CanHaveSuppressedWarnings x, Annotation... annotations) {
     x.setSuppressedWarnings(JdtUtil.getSuppressedWarnings(annotations));
   }
@@ -4137,9 +4142,9 @@
 
   private void createParameter(SourceInfo info, LocalVariableBinding binding, String name,
       JMethod method, boolean isVarargs, Annotation... annotations) {
-    JParameter param =
+    JParameter parameter =
         method.createParameter(info, name, typeMap.get(binding.type), binding.isFinal(), isVarargs);
-    processSuppressedWarnings(param, annotations);
+    processAnnotations(parameter, annotations);
   }
 
   private void createParameters(JMethod method, AbstractMethodDeclaration x) {
diff --git a/dev/core/src/com/google/gwt/dev/jjs/impl/JsInteropRestrictionChecker.java b/dev/core/src/com/google/gwt/dev/jjs/impl/JsInteropRestrictionChecker.java
index 583431e..0a0139f 100644
--- a/dev/core/src/com/google/gwt/dev/jjs/impl/JsInteropRestrictionChecker.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/impl/JsInteropRestrictionChecker.java
@@ -243,6 +243,10 @@
       checkIllegalOverrides(member);
     }
 
+    if (member instanceof JMethod) {
+      checkMethodParameters((JMethod) member);
+    }
+
     if (member.isJsOverlay()) {
       checkJsOverlay(member);
       return;
@@ -260,10 +264,6 @@
       return;
     }
 
-    if (member.isJsMethodVarargs()) {
-      checkJsVarargs(member);
-    }
-
     checkMemberQualifiedJsName(member);
 
     if (isCheckedLocalName(member)) {
@@ -307,33 +307,38 @@
       return;
     }
 
-    String methodDescription = JjsUtils.getReadableDescription(member);
+    String memberDescription = JjsUtils.getReadableDescription(member);
 
     if (!member.getEnclosingType().isJsNative()) {
-      logError(member, "JsOverlay '%s' can only be declared in a native type.", methodDescription);
+      logError(member, "JsOverlay '%s' can only be declared in a native type.", memberDescription);
+    }
+
+    if (member instanceof JConstructor) {
+      logError(member, "JsOverlay method '%s' cannot be a constructor.", memberDescription);
+      return;
+    }
+
+    if (member.getJsMemberType() != JsMemberType.NONE) {
+      logError(member, "JsOverlay method '%s' cannot be nor override a JsProperty or a JsMethod.",
+          memberDescription);
+      return;
     }
 
     if (member instanceof JField) {
       JField field = (JField) member;
       if (field.needsDynamicDispatch()) {
-        logError(
-            member, "JsOverlay field '%s' can only be static.",
-            methodDescription);
+        logError(member, "JsOverlay field '%s' can only be static.", memberDescription);
       }
       return;
     }
 
     JMethod method = (JMethod) member;
-    if (!method.getOverriddenMethods().isEmpty()) {
-      logError(member,
-          "JsOverlay method '%s' cannot override a supertype method.", methodDescription);
-      return;
-    }
+
+    assert method.getOverriddenMethods().isEmpty();
 
     if (method.getBody() == null || (!method.isFinal() && !method.isStatic()
         && !method.isDefaultMethod())) {
-      logError(member,
-          "JsOverlay method '%s' cannot be non-final nor native.", methodDescription);
+      logError(member, "JsOverlay method '%s' cannot be non-final nor native.", memberDescription);
     }
   }
 
@@ -380,8 +385,34 @@
     }
   }
 
-  private void checkJsVarargs(JMember member) {
-    final JMethod method = (JMethod) member;
+  private void checkMethodParameters(JMethod method) {
+    boolean hasOptionalParameters = false;
+    for (JParameter parameter : method.getParams()) {
+      if (parameter.isOptional()) {
+        hasOptionalParameters = true;
+        continue;
+      }
+      if (hasOptionalParameters && !parameter.isVarargs()) {
+        logError(method, "JsOptional parameter '%s' in method %s cannot precede parameters "
+            + "that are not optional.", parameter.getName(), getMemberDescription(method));
+        break;
+      }
+    }
+
+    if (hasOptionalParameters
+        && method.getJsMemberType() != JsMemberType.CONSTRUCTOR
+        && method.getJsMemberType() != JsMemberType.METHOD
+        && !method.isOrOverridesJsFunctionMethod()) {
+      logError(method, "Method %s has JsOptional parameters and is not a JsMethod, "
+          + "a JsConstructor or a JsFunction method.", getMemberDescription(method));
+    }
+
+    if (method.isJsMethodVarargs()) {
+      checkJsVarargs(method);
+    }
+  }
+
+  private void checkJsVarargs(final JMethod method) {
     if (!method.isJsniMethod()) {
       return;
     }
diff --git a/dev/core/test/com/google/gwt/dev/jjs/impl/JsInteropRestrictionCheckerTest.java b/dev/core/test/com/google/gwt/dev/jjs/impl/JsInteropRestrictionCheckerTest.java
index eb92871..3a35948 100644
--- a/dev/core/test/com/google/gwt/dev/jjs/impl/JsInteropRestrictionCheckerTest.java
+++ b/dev/core/test/com/google/gwt/dev/jjs/impl/JsInteropRestrictionCheckerTest.java
@@ -1496,7 +1496,84 @@
             + " method 'void EntryPoint.Interface.someOtherMethod()'.");
   }
 
-  public void testJsOverlayOnNativeJsTypeInterfaceSucceds() throws Exception {
+  public void testJsOptionalSucceeds() throws Exception {
+    addSnippetImport("jsinterop.annotations.JsConstructor");
+    addSnippetImport("jsinterop.annotations.JsMethod");
+    addSnippetImport("jsinterop.annotations.JsOptional");
+    addSnippetClassDecl(
+        "public static class Buggy {",
+        "  @JsConstructor public Buggy(@JsOptional Object a) {}",
+        "  @JsMethod public void fun(int a, Object b, @JsOptional String c) {}",
+        "  @JsMethod public void bar(int a, @JsOptional Object b, @JsOptional String c) {}",
+        "  @JsMethod public void baz(@JsOptional int a, @JsOptional Object b) {}",
+        "}");
+
+    assertBuggySucceeds();
+  }
+
+  public void testJsOptionalWithVarargsSucceeds() throws Exception {
+    addSnippetImport("jsinterop.annotations.JsMethod");
+    addSnippetImport("jsinterop.annotations.JsOptional");
+    addSnippetClassDecl(
+        "public class Buggy {",
+        "   @JsMethod public void fun(@JsOptional String c, Object... os) {}",
+        "   @JsMethod public void bar(int a, @JsOptional Object b, @JsOptional String... c) {}",
+        "}");
+
+    assertBuggySucceeds();
+  }
+
+  public void testJsOptionalNotAtEndFails() throws Exception {
+    addSnippetImport("jsinterop.annotations.JsConstructor");
+    addSnippetImport("jsinterop.annotations.JsMethod");
+    addSnippetImport("jsinterop.annotations.JsOptional");
+    addSnippetClassDecl(
+        "public static class Buggy {",
+        "   @JsConstructor public Buggy(@JsOptional int a, Object b, @JsOptional String c) {}",
+        "   @JsMethod public void bar(int a, @JsOptional Object b, String c) {}",
+        "   @JsMethod public void baz(@JsOptional Object b, String c, Object... os) {}",
+        "}");
+
+    assertBuggyFails(
+        "Line 7: JsOptional parameter 'b' in method 'EntryPoint.Buggy.EntryPoint$Buggy(int, "
+            + "Object, String)' cannot precede parameters that are not optional.",
+        "Line 8: JsOptional parameter 'c' in method 'void EntryPoint.Buggy.bar(int, Object,"
+            + " String)' cannot precede parameters that are not optional.",
+        "Line 9: JsOptional parameter 'c' in method 'void EntryPoint.Buggy.baz(Object, String, "
+            + "Object[])' cannot precede parameters that are not optional.");
+  }
+
+  public void testJsOptionalOnNonJsExposedMethodsFails() throws Exception {
+    addSnippetImport("jsinterop.annotations.JsProperty");
+    addSnippetImport("jsinterop.annotations.JsOptional");
+    addSnippetClassDecl(
+        "public static class Buggy {",
+        "  public void fun(int a, @JsOptional Object b, @JsOptional String c) {}",
+        "  @JsProperty public void setBar(@JsOptional Object o) {}",
+        "}");
+
+    assertBuggyFails(
+        "Line 6: Method 'void EntryPoint.Buggy.fun(int, Object, String)' has JsOptional parameters "
+            + "and is not a JsMethod, a JsConstructor or a JsFunction method.",
+        "Line 7: Method 'void EntryPoint.Buggy.setBar(Object)' has JsOptional parameters and is "
+            + "not a JsMethod, a JsConstructor or a JsFunction method.");
+  }
+
+  public void testJsOptionalOnJsOverlayMethodsFails() throws Exception {
+    addSnippetImport("jsinterop.annotations.JsType");
+    addSnippetImport("jsinterop.annotations.JsOptional");
+    addSnippetImport("jsinterop.annotations.JsOverlay");
+    addSnippetClassDecl(
+        "@JsType(isNative = true) public static class Buggy {",
+        "  @JsOverlay public final void fun(@JsOptional Object a) {}",
+        "}");
+
+    assertBuggyFails(
+        "Line 7: Method 'void EntryPoint.Buggy.fun(Object)' has JsOptional parameters and "
+            + "is not a JsMethod, a JsConstructor or a JsFunction method.");
+  }
+
+  public void testJsOverlayOnNativeJsTypeInterfaceSucceeds() throws Exception {
     addSnippetImport("jsinterop.annotations.JsType");
     addSnippetImport("jsinterop.annotations.JsOverlay");
     addSnippetClassDecl(
@@ -1538,8 +1615,8 @@
         "  @JsOverlay public void m() { }",
         "}");
 
-    assertBuggyFails("Line 9: JsOverlay method 'void EntryPoint.Buggy.m()' cannot override a "
-        + "supertype method.");
+    assertBuggyFails("Line 9: JsOverlay method 'void EntryPoint.Buggy.m()' cannot be nor override"
+        + " a JsProperty or a JsMethod.");
   }
 
   public void testJsOverlayOverridingSuperclassMethodFails() {
@@ -1553,8 +1630,8 @@
         "  @JsOverlay public void m() { }",
         "}");
 
-    assertBuggyFails(
-        "Line 9: JsOverlay method 'void EntryPoint.Buggy.m()' cannot override a supertype method.");
+    assertBuggyFails("Line 9: JsOverlay method 'void EntryPoint.Buggy.m()' cannot be nor override"
+        + " a JsProperty or a JsMethod.");
   }
 
   public void testJsOverlayOnNonFinalMethodAndInstanceFieldFails() {
@@ -1614,6 +1691,33 @@
     assertBuggySucceeds();
   }
 
+  public void testJsOverlayOnJsMemberFails() {
+    addSnippetImport("jsinterop.annotations.JsType");
+    addSnippetImport("jsinterop.annotations.JsOverlay");
+    addSnippetImport("jsinterop.annotations.JsMethod");
+    addSnippetImport("jsinterop.annotations.JsProperty");
+    addSnippetImport("jsinterop.annotations.JsConstructor");
+    addSnippetClassDecl(
+        "@JsType(isNative=true) public static class Buggy {",
+        "  @JsOverlay public Buggy() { }",
+        "  @JsOverlay @JsConstructor protected Buggy(int i) { }",
+        "  @JsMethod @JsOverlay public final void m() { }",
+        "  @JsMethod @JsOverlay public static void n() { }",
+        "  @JsProperty @JsOverlay public static void setA(String value) { }",
+        "}");
+
+    assertBuggyFails(
+        "Line 9: JsOverlay method 'EntryPoint.Buggy.EntryPoint$Buggy()' cannot be a constructor.",
+        "Line 10: JsOverlay method 'EntryPoint.Buggy.EntryPoint$Buggy(int)' cannot be a "
+            + "constructor.",
+        "Line 11: JsOverlay method 'void EntryPoint.Buggy.m()' cannot be nor override"
+            + " a JsProperty or a JsMethod.",
+        "Line 12: JsOverlay method 'void EntryPoint.Buggy.n()' cannot be nor override"
+            + " a JsProperty or a JsMethod.",
+        "Line 13: JsOverlay method 'void EntryPoint.Buggy.setA(String)' cannot be nor override"
+            + " a JsProperty or a JsMethod.");
+  }
+
   public void testImplicitJsOverlayOnJsoMethodSucceeds() throws Exception {
     addSnippetImport("com.google.gwt.core.client.JavaScriptObject");
     addSnippetImport("jsinterop.annotations.JsOverlay");