diff --git a/src/lib/bind/effects.html b/src/lib/bind/effects.html
index 2f987fa1..52ed42ed 100644
--- a/src/lib/bind/effects.html
+++ b/src/lib/bind/effects.html
@@ -66,6 +66,10 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
         if (args) {
           fn.apply(this, args);
         }
+      } else if (effect.dynamicFn) {
+        // dynamic functions can be just like every other property `undefined`
+        // so we MUST ignore an undefined value here. (That's totally the
+        // same guard we use within `_marshalArgs` and part of the spec.)
       } else {
         this._warn(this._logf('_complexObserverEffect', 'observer method `' +
           effect.method + '` not defined'));
@@ -73,15 +77,20 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
     },
 
     _computeEffect: function(source, value, effect) {
-      var args = Polymer.Bind._marshalArgs(this.__data__, effect, source, value);
-      if (args) {
-        var fn = this[effect.method];
-        if (fn) {
-          this.__setProperty(effect.name, fn.apply(this, args));
-        } else {
-          this._warn(this._logf('_computeEffect', 'compute method `' +
-            effect.method + '` not defined'));
+      var fn = this[effect.method];
+      if (fn) {
+        var args = Polymer.Bind._marshalArgs(this.__data__, effect, source, value);
+        if (args) {
+          var computedvalue = fn.apply(this, args);
+          this.__setProperty(effect.name, computedvalue);
         }
+      } else if (effect.dynamicFn) {
+        // dynamic functions can be just like every other property `undefined`
+        // so we MUST ignore an undefined value here. (That's totally the
+        // same guard we use within `_marshalArgs` and part of the spec.)
+      } else {
+        this._warn(this._logf('_computeEffect', 'compute method `' +
+          effect.method + '` not defined'));
       }
     },
 
@@ -97,6 +106,10 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
           }
           this._applyEffectValue(effect, computedvalue);
         }
+      } else if (effect.dynamicFn) {
+        // dynamic functions can be just like every other property `undefined`
+        // so we MUST ignore an undefined value here. (That's totally the
+        // same guard we use within `_marshalArgs` and part of the spec.)
       } else {
         computedHost._warn(computedHost._logf('_annotatedComputationEffect',
           'compute method `' + effect.method + '` not defined'));
@@ -108,6 +121,9 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
     _marshalArgs: function(model, effect, path, value) {
       var values = [];
       var args = effect.args;
+      // Actually we should return early as soon as we see an `undefined`,
+      // but dom-repeat relies on this behavior.
+      var bailoutEarly = (args.length > 1 || effect.dynamicFn);
       for (var i=0, l=args.length; i<l; i++) {
         var arg = args[i];
         var name = arg.name;
@@ -119,7 +135,7 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
         } else {
           v = model[name];
         }
-        if (args.length > 1 && v === undefined) {
+        if (bailoutEarly && v === undefined) {
           return;
         }
         if (arg.wildcard) {
diff --git a/src/standard/annotations.html b/src/standard/annotations.html
index 7c845c67..3743c48a 100644
--- a/src/standard/annotations.html
+++ b/src/standard/annotations.html
@@ -145,8 +145,10 @@ TODO(sjmiles): this module should produce either syntactic metadata
           for (var k=0; k<b.parts.length; k++) {
             var p = b.parts[k];
             if (!p.literal) {
-              p.signature = this._parseMethod(p.value);
-              if (!p.signature) {
+              var signature = this._parseMethod(p.value);
+              if (signature) {
+                p.signature = signature;
+              } else {
                 p.model = this._modelForPath(p.value);
               }
             }
diff --git a/src/standard/effectBuilder.html b/src/standard/effectBuilder.html
index f47ef37b..89e064b2 100644
--- a/src/standard/effectBuilder.html
+++ b/src/standard/effectBuilder.html
@@ -79,14 +79,27 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
 
     _addComputedEffect: function(name, expression) {
       var sig = this._parseMethod(expression);
+
+      var dynamicFn = sig.dynamicFn;
+
       for (var i=0, arg; (i<sig.args.length) && (arg=sig.args[i]); i++) {
         this._addPropertyEffect(arg.model, 'compute', {
           method: sig.method,
           args: sig.args,
           trigger: arg,
-          name: name
+          name: name,
+          dynamicFn: dynamicFn
         });
       }
+      if (dynamicFn) {
+        this._addPropertyEffect(sig.method, 'compute', {
+          method: sig.method,
+          args: sig.args,
+          trigger: null,
+          name: name,
+          dynamicFn: dynamicFn
+        })
+      }
     },
 
     _addObserverEffect: function(property, observer) {
@@ -111,11 +124,22 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
         throw new Error("Malformed observer expression '" + observer + "'");
       }
 
+      var dynamicFn = sig.dynamicFn;
+
       for (var i=0, arg; (i<sig.args.length) && (arg=sig.args[i]); i++) {
         this._addPropertyEffect(arg.model, 'complexObserver', {
           method: sig.method,
           args: sig.args,
-          trigger: arg
+          trigger: arg,
+          dynamicFn: dynamicFn
+        });
+      }
+      if (dynamicFn) {
+        this._addPropertyEffect(sig.method, 'complexObserver', {
+          method: sig.method,
+          args: sig.args,
+          trigger: null,
+          dynamicFn: dynamicFn
         });
       }
     },
@@ -171,6 +195,14 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
               arg);
           }
         }
+        if (sig.dynamicFn) {
+          // trigger=null is sufficient as long as we don't allow paths to be
+          // used. If we change our mind, we must first implement this in the
+          // effects anyway where we basically do a `fn = this[methodName]` at
+          // the moment.
+          this.__addAnnotatedComputationEffect(
+              sig.method, index, note, part, null);
+        }
       }
     },
 
@@ -184,7 +216,8 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
         negate: part.negate,
         method: part.signature.method,
         args: part.signature.args,
-        trigger: trigger
+        trigger: trigger,
+        dynamicFn: part.signature.dynamicFn
       });
     },
 
@@ -194,6 +227,11 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
       var m = expression.match(/([^\s]+?)\(([\s\S]*)\)/);
       if (m) {
         var sig = { method: m[1], static: true };
+        // TODO(kaste): Optimize/memoize `getPropertyInfo`.
+        if (this.getPropertyInfo(sig.method) !== Polymer.nob) {
+          sig.static = false;
+          sig.dynamicFn = true;
+        }
         if (m[2].trim()) {
           // replace escaped commas with comma entity, split on un-escaped commas
           var args = m[2].replace(/\\,/g, '&comma;').split(',');
diff --git a/test/unit/bind-elements.html b/test/unit/bind-elements.html
index b58f7afc..06f09207 100644
--- a/test/unit/bind-elements.html
+++ b/test/unit/bind-elements.html
@@ -588,3 +588,73 @@
   })();
   </script>
 </dom-module>
+
+<dom-module id="x-bind-computed-property">
+  <template>
+    <div id="check">[[translate('Hello World.')]]</div>
+  </template>
+  <script>
+    (function(){
+      var TranslateBehavior = {
+        properties: {
+          translate: {
+            type: Function,
+            computed: '_computeTranslateFn(translator)'
+          }
+        }
+      };
+      Polymer({
+        is: 'x-bind-computed-property',
+        behaviors: [TranslateBehavior],
+        properties: {
+          translator: {
+            type: Function,
+            value: function() {
+              return function(message) {
+                return 'translated: ' + message;
+              }
+            }
+          },
+        },
+
+        _computeTranslateFn: function(translator) {
+          return function(message) {
+            return translator(message);
+          }
+        },
+
+      });
+    })();
+  </script>
+</dom-module>
+
+<dom-module id="x-bind-computed-property-late-translator">
+  <template>
+    <div id="check">[[translate(message)]]</div>
+  </template>
+  <script>
+    Polymer({
+      is: 'x-bind-computed-property-late-translator',
+      properties: {
+        message: {
+          type: String,
+          value: 'Hello'
+        },
+        translate: {
+          type: Function,
+          computed: '_computeTranslateFn(translator)'
+        },
+        translator: {
+          type: Function,
+        },
+      },
+
+      _computeTranslateFn: function(translator) {
+        return function(message) {
+          return translator(message);
+        }
+      },
+
+    });
+  </script>
+</dom-module>
\ No newline at end of file
diff --git a/test/unit/bind.html b/test/unit/bind.html
index fcc31d15..d744ac07 100644
--- a/test/unit/bind.html
+++ b/test/unit/bind.html
@@ -285,6 +285,107 @@ suite('single-element binding effects', function() {
 
 <script>
 
+suite('computed bindings with dynamic functions', function() {
+
+  var el;
+
+  setup(function() {
+
+  });
+
+  teardown(function() {
+    document.body.removeChild(el);
+  });
+
+  test('annotated computation with dynamic function', function() {
+    el = document.createElement('x-bind-computed-property');
+    document.body.appendChild(el);
+
+    assert.equal(el.$.check.textContent, 'translated: Hello World.');
+
+    el.translator = function(message) {
+      return 'changed: ' + message;
+    }
+
+    assert.equal(el.$.check.textContent, 'changed: Hello World.');
+  });
+
+  test('annotated computation / late resolved dynamic function', function() {
+    el = document.createElement('x-bind-computed-property-late-translator');
+    document.body.appendChild(el);
+
+    assert.equal(el.$.check.textContent.trim(), '');
+
+    el.translator = function(message) {
+      return 'translated: ' + message;
+    };
+
+    assert.equal(el.$.check.textContent, 'translated: Hello');
+  });
+
+  test('observer with dynamic function', function() {
+    Polymer({
+      is: 'x-observer-with-dynamic-function',
+      properties: {
+        translate: {
+          type: Function,
+        },
+        message: {
+          type: String,
+          value: 'Hello'
+        },
+      },
+
+      observers: ['translate(message)'],
+
+    })
+
+    el = document.createElement('x-observer-with-dynamic-function');
+    document.body.appendChild(el);
+
+    var called = 0;
+    el.translate = function() {
+      called += 1;
+    };
+
+    assert.equal(called, 1);
+
+  });
+
+  test('computed property with dynamic function', function() {
+    Polymer({
+      is: 'x-computed-property-with-dynamic-function',
+      properties: {
+        computedValue: {
+          computed: "translate('Hello')"
+        },
+        translate: {
+          type: Function
+        }
+      }
+    });
+
+    el = document.createElement('x-computed-property-with-dynamic-function');
+    document.body.appendChild(el);
+
+    assert.equal(el.computedValue, undefined);
+
+    var called = 0;
+    el.translate = function(message) {
+      called += 1;
+      return 'translated: ' + message;
+    };
+
+    assert.equal(called, 1);
+    assert.equal(el.computedValue, 'translated: Hello');
+
+  });
+
+});
+
+</script>
+
+<script>
 suite('2-way binding effects between elements', function() {
 
   var el;