diff --git a/components/script/dom/webidls/CSSStyleDeclaration.webidl b/components/script/dom/webidls/CSSStyleDeclaration.webidl
index cf7c3ade7f2..b656fc15e43 100644
--- a/components/script/dom/webidls/CSSStyleDeclaration.webidl
+++ b/components/script/dom/webidls/CSSStyleDeclaration.webidl
@@ -327,4 +327,7 @@ partial interface CSSStyleDeclaration {
   [SetterThrows, TreatNullAs=EmptyString] attribute DOMString flex-shrink;
   [SetterThrows, TreatNullAs=EmptyString] attribute DOMString alignSelf;
   [SetterThrows, TreatNullAs=EmptyString] attribute DOMString align-self;
+
+  [SetterThrows, TreatNullAs=EmptyString] attribute DOMString animation-name;
+  [SetterThrows, TreatNullAs=EmptyString] attribute DOMString animationName;
 };
diff --git a/components/style/animation.rs b/components/style/animation.rs
index 4a399a973f5..3cd994af327 100644
--- a/components/style/animation.rs
+++ b/components/style/animation.rs
@@ -817,7 +817,7 @@ fn can_interpolate_list(from_list: &[TransformOperation],
 fn interpolate_transform_list(from_list: &[TransformOperation],
                               to_list: &[TransformOperation],
                               time: f64) -> TransformList {
-    let mut result = vec!();
+    let mut result = vec![];
 
     if can_interpolate_list(from_list, to_list) {
         for (from, to) in from_list.iter().zip(to_list) {
diff --git a/components/style/matching.rs b/components/style/matching.rs
index 31d12ce4312..2e4b7922f7e 100644
--- a/components/style/matching.rs
+++ b/components/style/matching.rs
@@ -6,8 +6,8 @@
 
 #![allow(unsafe_code)]
 
-use animation::{self, Animation};
-use context::SharedStyleContext;
+use animation;
+use context::{SharedStyleContext, LocalStyleContext};
 use data::PrivateStyleData;
 use dom::{TElement, TNode, TRestyleDamage};
 use properties::{ComputedValues, PropertyDeclaration, cascade};
@@ -21,8 +21,7 @@ use smallvec::SmallVec;
 use std::collections::HashMap;
 use std::hash::{BuildHasherDefault, Hash, Hasher};
 use std::slice::Iter;
-use std::sync::mpsc::Sender;
-use std::sync::{Arc, Mutex};
+use std::sync::Arc;
 use string_cache::{Atom, Namespace};
 use util::arc_ptr_eq;
 use util::cache::{LRUCache, SimpleHashCache};
@@ -366,6 +365,10 @@ pub enum StyleSharingResult<ConcreteRestyleDamage: TRestyleDamage> {
 
 trait PrivateMatchMethods: TNode
     where <Self::ConcreteElement as Element>::Impl: SelectorImplExt {
+    /// Actually cascades style for a node or a pseudo-element of a node.
+    ///
+    /// Note that animations only apply to nodes or ::before or ::after
+    /// pseudo-elements.
     fn cascade_node_pseudo_element(&self,
                                    context: &SharedStyleContext<<Self::ConcreteElement as Element>::Impl>,
                                    parent_style: Option<&Arc<Self::ConcreteComputedValues>>,
@@ -373,13 +376,14 @@ trait PrivateMatchMethods: TNode
                                    mut style: Option<&mut Arc<Self::ConcreteComputedValues>>,
                                    applicable_declarations_cache:
                                     &mut ApplicableDeclarationsCache<Self::ConcreteComputedValues>,
-                                   new_animations_sender: &Mutex<Sender<Animation>>,
                                    shareable: bool,
                                    animate_properties: bool)
                                    -> (Self::ConcreteRestyleDamage, Arc<Self::ConcreteComputedValues>) {
         let mut cacheable = true;
+        let mut animations = None;
         if animate_properties {
             cacheable = !self.update_animations_for_cascade(context, &mut style) && cacheable;
+            animations = Some(context.stylist.animations())
         }
 
         let mut this_style;
@@ -387,14 +391,16 @@ trait PrivateMatchMethods: TNode
             Some(ref parent_style) => {
                 let cache_entry = applicable_declarations_cache.find(applicable_declarations);
                 let cached_computed_values = match cache_entry {
-                    None => None,
                     Some(ref style) => Some(&**style),
+                    None => None,
                 };
+
                 let (the_style, is_cacheable) = cascade(context.viewport_size,
                                                         applicable_declarations,
                                                         shareable,
                                                         Some(&***parent_style),
                                                         cached_computed_values,
+                                                        animations,
                                                         context.error_reporter.clone());
                 cacheable = cacheable && is_cacheable;
                 this_style = the_style
@@ -405,6 +411,7 @@ trait PrivateMatchMethods: TNode
                                                         shareable,
                                                         None,
                                                         None,
+                                                        animations,
                                                         context.error_reporter.clone());
                 cacheable = cacheable && is_cacheable;
                 this_style = the_style
@@ -417,7 +424,7 @@ trait PrivateMatchMethods: TNode
             if let Some(ref style) = style {
                 let animations_started =
                     animation::start_transitions_if_applicable::<Self::ConcreteComputedValues>(
-                        new_animations_sender,
+                        &context.new_animations_sender,
                         self.opaque(),
                         &**style,
                         &mut this_style);
@@ -641,11 +648,9 @@ pub trait MatchMethods : TNode {
 
     unsafe fn cascade_node(&self,
                            context: &SharedStyleContext<<Self::ConcreteElement as Element>::Impl>,
+                           local_context: &LocalStyleContext<Self::ConcreteComputedValues>,
                            parent: Option<Self>,
-                           applicable_declarations: &ApplicableDeclarations<<Self::ConcreteElement as Element>::Impl>,
-                           applicable_declarations_cache:
-                             &mut ApplicableDeclarationsCache<Self::ConcreteComputedValues>,
-                           new_animations_sender: &Mutex<Sender<Animation>>)
+                           applicable_declarations: &ApplicableDeclarations<<Self::ConcreteElement as Element>::Impl>)
                            where <Self::ConcreteElement as Element>::Impl: SelectorImplExt {
         // Get our parent's style. This must be unsafe so that we don't touch the parent's
         // borrow flags.
@@ -653,13 +658,16 @@ pub trait MatchMethods : TNode {
         // FIXME(pcwalton): Isolate this unsafety into the `wrapper` module to allow
         // enforced safe, race-free access to the parent style.
         let parent_style = match parent {
-            None => None,
             Some(parent_node) => {
                 let parent_style = (*parent_node.borrow_data_unchecked().unwrap()).style.as_ref().unwrap();
                 Some(parent_style)
             }
+            None => None,
         };
 
+        let mut applicable_declarations_cache =
+            local_context.applicable_declarations_cache.borrow_mut();
+
         let damage;
         if self.is_text_node() {
             let mut data_ref = self.mutate_data().unwrap();
@@ -677,8 +685,7 @@ pub trait MatchMethods : TNode {
                     parent_style,
                     &applicable_declarations.normal,
                     data.style.as_mut(),
-                    applicable_declarations_cache,
-                    new_animations_sender,
+                    &mut applicable_declarations_cache,
                     applicable_declarations.normal_shareable,
                     true);
 
@@ -690,15 +697,18 @@ pub trait MatchMethods : TNode {
 
 
                     if !applicable_declarations_for_this_pseudo.is_empty() {
+                        // NB: Transitions and animations should only work for
+                        // pseudo-elements ::before and ::after
+                        let should_animate_properties =
+                            <Self::ConcreteElement as Element>::Impl::pseudo_is_before_or_after(&pseudo);
                         let (new_damage, style) = self.cascade_node_pseudo_element(
                             context,
                             Some(data.style.as_ref().unwrap()),
                             &*applicable_declarations_for_this_pseudo,
                             data.per_pseudo.get_mut(&pseudo),
-                            applicable_declarations_cache,
-                            new_animations_sender,
+                            &mut applicable_declarations_cache,
                             false,
-                            false);
+                            should_animate_properties);
                         data.per_pseudo.insert(pseudo, style);
 
                         damage = damage | new_damage;
diff --git a/components/style/properties/longhand/box.mako.rs b/components/style/properties/longhand/box.mako.rs
index c1eba31c3a3..4d50e99594f 100644
--- a/components/style/properties/longhand/box.mako.rs
+++ b/components/style/properties/longhand/box.mako.rs
@@ -795,6 +795,77 @@ ${helpers.single_keyword("overflow-x", "visible hidden scroll auto", need_clone=
     pub use properties::longhands::transition_duration::{get_initial_value, parse, parse_one};
 </%helpers:longhand>
 
+<%helpers:longhand name="animation-name" experimental="True">
+    use cssparser::ToCss;
+    use std::borrow::Cow;
+    use std::fmt;
+
+    pub mod computed_value {
+        use cssparser::ToCss;
+        use std::fmt;
+
+        #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+        pub struct T(pub Vec<String>);
+
+        impl ToCss for T {
+            fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+                for (i, name) in self.0.iter().enumerate() {
+                    if i != 0 {
+                        try!(dest.write_str(", "));
+                    }
+                    try!(dest.write_str(&name));
+                }
+                Ok(())
+            }
+        }
+    }
+
+    // TODO: Use Cows? Probably more codegen work would be needed, and this
+    // could not be that worth it (animations arent *that* used).
+    #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+    pub struct SpecifiedValue(Vec<String>);
+
+    impl ToCss for SpecifiedValue {
+        fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+            for (i, name) in self.0.iter().enumerate() {
+                if i != 0 {
+                    try!(dest.write_str(", "));
+                }
+                try!(dest.write_str(&name));
+            }
+            Ok(())
+        }
+    }
+
+    #[inline]
+    pub fn get_initial_value() -> computed_value::T {
+        computed_value::T(vec![])
+    }
+
+    pub fn parse(_: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue,()> {
+        Ok(SpecifiedValue(try!(input.parse_comma_separated(|input| {
+            input.expect_ident().map(Cow::into_owned)
+        }))))
+    }
+
+    impl ToComputedValue for SpecifiedValue {
+        type ComputedValue = computed_value::T;
+
+        #[inline]
+        fn to_computed_value<Cx: TContext>(&self, context: &Cx) -> computed_value::T {
+            let mut ret = vec![];
+            if let Some(animations) = context.animations() {
+                for name in self.0.iter() {
+                    if animations.contains_key(&**name) {
+                        ret.push(name.clone());
+                    }
+                }
+            }
+            computed_value::T(ret)
+        }
+    }
+</%helpers:longhand>
+
 // CSSOM View Module
 // https://www.w3.org/TR/cssom-view-1/
 ${helpers.single_keyword("scroll-behavior",
diff --git a/components/style/properties/properties.mako.rs b/components/style/properties/properties.mako.rs
index 2e5ab399482..3df108e0e6a 100644
--- a/components/style/properties/properties.mako.rs
+++ b/components/style/properties/properties.mako.rs
@@ -12,7 +12,7 @@
 
 use std::ascii::AsciiExt;
 use std::boxed::Box as StdBox;
-use std::collections::HashSet;
+use std::collections::{HashMap, HashSet};
 use std::fmt;
 use std::fmt::Write;
 use std::sync::Arc;
@@ -22,6 +22,7 @@ use cssparser::Color as CSSParserColor;
 use cssparser::{Parser, RGBA, AtRuleParser, DeclarationParser, Delimiter,
                 DeclarationListParser, parse_important, ToCss, TokenSerializationType};
 use error_reporting::ParseErrorReporter;
+use keyframes::Keyframe;
 use url::Url;
 use euclid::side_offsets::SideOffsets2D;
 use euclid::size::Size2D;
@@ -1594,12 +1595,14 @@ fn cascade_with_cached_declarations<C: ComputedValues>(
         parent_style: &C,
         cached_style: &C,
         custom_properties: Option<Arc<::custom_properties::ComputedValuesMap>>,
+        animations: Option<<&HashMap<String, Vec<Keyframe>>>,
         mut error_reporter: StdBox<ParseErrorReporter + Send>)
         -> C {
     let mut context = computed::Context {
         is_root_element: false,
         viewport_size: viewport_size,
         inherited_style: parent_style,
+        animations: animations,
         style: C::new(
             custom_properties,
             shareable,
@@ -1739,6 +1742,7 @@ pub fn cascade<C: ComputedValues>(
                shareable: bool,
                parent_style: Option<<&C>,
                cached_style: Option<<&C>,
+               animations: Option<<&HashMap<String, Vec<Keyframe>>>,
                mut error_reporter: StdBox<ParseErrorReporter + Send>)
                -> (C, bool) {
     use properties::style_struct_traits::{Border, Box, Font, Outline};
@@ -1774,6 +1778,7 @@ pub fn cascade<C: ComputedValues>(
                                                      parent_style,
                                                      cached_style,
                                                      custom_properties,
+                                                     animations,
                                                      error_reporter);
         return (style, false)
     }
@@ -1782,6 +1787,7 @@ pub fn cascade<C: ComputedValues>(
         is_root_element: is_root_element,
         viewport_size: viewport_size,
         inherited_style: inherited_style,
+        animations: animations,
         style: C::new(
             custom_properties,
             shareable,
diff --git a/components/style/selector_impl.rs b/components/style/selector_impl.rs
index 29e3fa36927..a394ef987cc 100644
--- a/components/style/selector_impl.rs
+++ b/components/style/selector_impl.rs
@@ -90,6 +90,7 @@ pub trait SelectorImplExt : SelectorImpl + Sized {
         })
     }
 
+    fn pseudo_is_before_or_after(pseudo: &Self::PseudoElement) -> bool;
 
     fn pseudo_class_state_flag(pc: &Self::NonTSPseudoClass) -> ElementState;
 
@@ -109,6 +110,15 @@ pub enum PseudoElement {
 }
 
 impl PseudoElement {
+    #[inline]
+    pub fn is_before_or_after(&self) -> bool {
+        match *self {
+            PseudoElement::Before |
+            PseudoElement::After => true,
+            _ => false,
+        }
+    }
+
     #[inline]
     pub fn cascade_type(&self) -> PseudoElementCascadeType {
         match *self {
@@ -249,6 +259,11 @@ impl SelectorImplExt for ServoSelectorImpl {
         pc.state_flag()
     }
 
+    #[inline]
+    fn pseudo_is_before_or_after(pseudo: &PseudoElement) -> bool {
+        pseudo.is_before_or_after()
+    }
+
     #[inline]
     fn get_user_or_user_agent_stylesheets() -> &'static [Stylesheet<Self>] {
         &*USER_OR_USER_AGENT_STYLESHEETS
diff --git a/components/style/selector_matching.rs b/components/style/selector_matching.rs
index 64bf1b38863..a3fe67b1b75 100644
--- a/components/style/selector_matching.rs
+++ b/components/style/selector_matching.rs
@@ -128,9 +128,7 @@ pub struct Stylist<Impl: SelectorImplExt> {
                          BuildHasherDefault<::fnv::FnvHasher>>,
 
     /// A map with all the animations indexed by name.
-    animations: HashMap<String,
-                        Vec<Keyframe>,
-                        BuildHasherDefault<::fnv::FnvHasher>>,
+    animations: HashMap<String, Vec<Keyframe>>,
 
     /// Applicable declarations for a given non-eagerly cascaded pseudo-element.
     /// These are eagerly computed once, and then used to resolve the new
@@ -290,7 +288,8 @@ impl<Impl: SelectorImplExt> Stylist<Impl> {
             let (computed, _) =
                 properties::cascade(self.device.au_viewport_size(),
                                     &declarations, false,
-                                    parent.map(|p| &**p), None,
+                                    parent.map(|p| &**p),
+                                    None, None,
                                     Box::new(StdoutErrorReporter));
             Some(Arc::new(computed))
         } else {
@@ -323,7 +322,7 @@ impl<Impl: SelectorImplExt> Stylist<Impl> {
         let (computed, _) =
             properties::cascade(self.device.au_viewport_size(),
                                 &declarations, false,
-                                Some(&**parent), None,
+                                Some(&**parent), None, None,
                                 Box::new(StdoutErrorReporter));
         Some(Arc::new(computed))
     }
@@ -457,6 +456,11 @@ impl<Impl: SelectorImplExt> Stylist<Impl> {
     pub fn is_device_dirty(&self) -> bool {
         self.is_device_dirty
     }
+
+    #[inline]
+    pub fn animations(&self) -> &HashMap<String, Vec<Keyframe>> {
+        &self.animations
+    }
 }
 
 /// Map that contains the CSS rules for a given origin.
diff --git a/components/style/stylesheets.rs b/components/style/stylesheets.rs
index 09be8f542dd..c4a2ca24c3b 100644
--- a/components/style/stylesheets.rs
+++ b/components/style/stylesheets.rs
@@ -278,7 +278,6 @@ pub mod rule_filter {
 
             impl<'a, I, Impl: SelectorImpl + 'a> $variant<'a, I>
                 where I: Iterator<Item=&'a CSSRule<Impl>> {
-
                 #[inline]
                 pub fn new(iter: I) -> $variant<'a, I> {
                     $variant {
diff --git a/components/style/traversal.rs b/components/style/traversal.rs
index 281806e2263..5e5b7d31948 100644
--- a/components/style/traversal.rs
+++ b/components/style/traversal.rs
@@ -219,10 +219,9 @@ pub fn recalc_style_at<'a, N, C>(context: &'a C,
                 // Perform the CSS cascade.
                 unsafe {
                     node.cascade_node(&context.shared_context(),
+                                      &context.local_context(),
                                       parent_opt,
-                                      &applicable_declarations,
-                                      &mut context.local_context().applicable_declarations_cache.borrow_mut(),
-                                      &context.shared_context().new_animations_sender);
+                                      &applicable_declarations);
                 }
 
                 // Add ourselves to the LRU cache.
diff --git a/components/style/values.rs b/components/style/values.rs
index f515a403ab4..0a62485a185 100644
--- a/components/style/values.rs
+++ b/components/style/values.rs
@@ -1561,8 +1561,10 @@ pub mod specified {
 pub mod computed {
     use app_units::Au;
     use euclid::size::Size2D;
+    use keyframes::Keyframe;
     use properties::ComputedValues;
     use properties::style_struct_traits::Font;
+    use std::collections::HashMap;
     use std::fmt;
     use super::LocalToCss;
     use super::specified::AngleOrCorner;
@@ -1578,6 +1580,7 @@ pub mod computed {
         fn inherited_style(&self) -> &Self::ConcreteComputedValues;
         fn style(&self) -> &Self::ConcreteComputedValues;
         fn mutate_style(&mut self) -> &mut Self::ConcreteComputedValues;
+        fn animations(&self) -> Option<&HashMap<String, Vec<Keyframe>>>;
     }
 
     pub struct Context<'a, C: ComputedValues> {
@@ -1585,6 +1588,7 @@ pub mod computed {
         pub viewport_size: Size2D<Au>,
         pub inherited_style: &'a C,
 
+        pub animations: Option<&'a HashMap<String, Vec<Keyframe>>>,
         /// Values access through this need to be in the properties "computed early":
         /// color, text-decoration, font-size, display, position, float, border-*-style, outline-style
         pub style: C,
@@ -1597,6 +1601,7 @@ pub mod computed {
         fn inherited_style(&self) -> &C { &self.inherited_style }
         fn style(&self) -> &C { &self.style }
         fn mutate_style(&mut self) -> &mut C { &mut self.style }
+        fn animations(&self) -> Option<&HashMap<String, Vec<Keyframe>>> { self.animations }
     }
 
     pub trait ToComputedValue {
diff --git a/components/style/viewport.rs b/components/style/viewport.rs
index f763600d399..1707721a362 100644
--- a/components/style/viewport.rs
+++ b/components/style/viewport.rs
@@ -562,8 +562,8 @@ pub trait MaybeNew {
 
 impl MaybeNew for ViewportConstraints {
     fn maybe_new(initial_viewport: TypedSize2D<ViewportPx, f32>,
-                     rule: &ViewportRule)
-                     -> Option<ViewportConstraints>
+                 rule: &ViewportRule)
+                 -> Option<ViewportConstraints>
     {
         use std::cmp;
 
@@ -648,6 +648,7 @@ impl MaybeNew for ViewportConstraints {
             viewport_size: initial_viewport,
             inherited_style: ServoComputedValues::initial_values(),
             style: ServoComputedValues::initial_values().clone(),
+            animations: None,
         };
 
         // DEVICE-ADAPT § 9.3 Resolving 'extend-to-zoom'
diff --git a/ports/geckolib/selector_impl.rs b/ports/geckolib/selector_impl.rs
index 1c315df24c1..dda81ecec06 100644
--- a/ports/geckolib/selector_impl.rs
+++ b/ports/geckolib/selector_impl.rs
@@ -379,6 +379,15 @@ impl SelectorImplExt for GeckoSelectorImpl {
         fun(AnonBox(MozSVGText));
     }
 
+    #[inline]
+    fn pseudo_is_before_or_after(pseudo: &PseudoElement) -> bool {
+        match *pseudo {
+            PseudoElement::Before |
+            PseudoElement::After => true,
+            _ => false,
+        }
+    }
+
     #[inline]
     fn pseudo_class_state_flag(pc: &NonTSPseudoClass) -> ElementState {
         pc.state_flag()