diff --git a/src/Microsoft.DotNet.CodeFormatting.Tests/Microsoft.DotNet.CodeFormatting.Tests.csproj b/src/Microsoft.DotNet.CodeFormatting.Tests/Microsoft.DotNet.CodeFormatting.Tests.csproj
index 9cd7cd8c..afcb7a2c 100644
--- a/src/Microsoft.DotNet.CodeFormatting.Tests/Microsoft.DotNet.CodeFormatting.Tests.csproj
+++ b/src/Microsoft.DotNet.CodeFormatting.Tests/Microsoft.DotNet.CodeFormatting.Tests.csproj
@@ -105,6 +105,8 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="CodeFormattingTestBase.cs" />
+    <Compile Include="Rules\AttributeNoParenthesesRuleTests.cs" />
+    <Compile Include="Rules\AttributeSeparateListsRuleTests.cs" />
     <Compile Include="Rules\BracesRuleTests.cs" />
     <Compile Include="Rules\CombinationTest.cs" />
     <Compile Include="Rules\ExplicitThisRuleTests.cs" />
diff --git a/src/Microsoft.DotNet.CodeFormatting.Tests/Rules/AttributeNoParenthesesRuleTests.cs b/src/Microsoft.DotNet.CodeFormatting.Tests/Rules/AttributeNoParenthesesRuleTests.cs
new file mode 100644
index 00000000..6a88f27e
--- /dev/null
+++ b/src/Microsoft.DotNet.CodeFormatting.Tests/Rules/AttributeNoParenthesesRuleTests.cs
@@ -0,0 +1,61 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+
+using Microsoft.DotNet.CodeFormatting.Rules;
+
+using Xunit;
+
+namespace Microsoft.DotNet.CodeFormatting.Tests
+{
+    public class AttributeNoParenthesesRuleTests : SyntaxRuleTestBase
+    {
+        internal override ISyntaxFormattingRule Rule
+        {
+            get { return new AttributeNoParenthesesRule(); }
+        }
+
+        [Fact]
+        public void RemoveParenthesesFromAttributes()
+        {
+            var text = @"
+[assembly: GlobalAtt()]
+[assembly: GlobalAtt(1)]
+
+namespace Namespace1
+{
+    [Serializable(), Category(2), Rule]
+    class Class1
+    {
+        [return: SomeAtt(]
+        [AnotherAtt(1), YetAnotherAtt(), YetAnotherAtt]
+        public int SomeMethod(SyntaxNode syntaxRoot)
+        {
+            return 42;
+        }
+    }
+}
+";
+            var expected = @"
+[assembly: GlobalAtt]
+[assembly: GlobalAtt(1)]
+
+namespace Namespace1
+{
+    [Serializable, Category(2), Rule]
+    class Class1
+    {
+        [return: SomeAtt]
+        [AnotherAtt(1), YetAnotherAtt, YetAnotherAtt]
+        public int SomeMethod(SyntaxNode syntaxRoot)
+        {
+            return 42;
+        }
+    }
+}
+";
+            Verify(text, expected);
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/Microsoft.DotNet.CodeFormatting.Tests/Rules/AttributeSeparateListsRuleTests.cs b/src/Microsoft.DotNet.CodeFormatting.Tests/Rules/AttributeSeparateListsRuleTests.cs
new file mode 100644
index 00000000..3668ccc0
--- /dev/null
+++ b/src/Microsoft.DotNet.CodeFormatting.Tests/Rules/AttributeSeparateListsRuleTests.cs
@@ -0,0 +1,79 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+
+using Microsoft.DotNet.CodeFormatting.Rules;
+
+using Xunit;
+
+namespace Microsoft.DotNet.CodeFormatting.Tests
+{
+    public class AttributeSeparateListsRuleTests : SyntaxRuleTestBase
+    {
+        internal override ISyntaxFormattingRule Rule
+        {
+            get { return new AttributeSeparateListsRule(); }
+        }
+
+        [Fact]
+        public void ParameterAttributeListsAreNotSeparated()
+        {
+            var text = @"
+namespace Namespace1
+{
+    class Class1
+    {
+        public int SomeMethod([In, Out]SomeType someParameter)
+        {
+            return 42;
+        }
+    }
+}";
+            Verify(text, text);
+        }
+
+        [Fact]
+        public void AttributeListsAreSeparated()
+        {
+            var text = @"
+[assembly: FileVersion(1, 1), AssemblyVersion(1, 1)]
+namespace Namespace1
+{
+    [
+        Serializable,       // Good, isn't?
+        DefaultValue(1)     // Is this the right value?
+    ]
+    class Class1
+    {
+        [Serializable, DefaultValue(1)]
+        public int SomeMethod(SomeType someParameter)
+        {
+            return 42;
+        }
+    }
+}";
+
+            var expected = @"
+[assembly: FileVersion(1, 1)]
+[assembly: AssemblyVersion(1, 1)]
+namespace Namespace1
+{
+
+    [Serializable]       // Good, isn't?
+    [DefaultValue(1)]     // Is this the right value?
+
+    class Class1
+    {
+        [Serializable]
+        [DefaultValue(1)]
+        public int SomeMethod(SomeType someParameter)
+        {
+            return 42;
+        }
+    }
+}";
+            Verify(text, expected);
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/Microsoft.DotNet.CodeFormatting/Microsoft.DotNet.CodeFormatting.csproj b/src/Microsoft.DotNet.CodeFormatting/Microsoft.DotNet.CodeFormatting.csproj
index d5eedfb2..a0f2a1af 100644
--- a/src/Microsoft.DotNet.CodeFormatting/Microsoft.DotNet.CodeFormatting.csproj
+++ b/src/Microsoft.DotNet.CodeFormatting/Microsoft.DotNet.CodeFormatting.csproj
@@ -86,6 +86,8 @@
     <Compile Include="RuleOrderAttribute.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="IOrderMetadata.cs" />
+    <Compile Include="Rules\AttributeNoParenthesesRule.cs" />
+    <Compile Include="Rules\AttributeSeparateListsRule.cs" />
     <Compile Include="Rules\BraceNewLineRule.cs" />
     <Compile Include="Rules\ExplicitVisibilityRule.cs" />
     <Compile Include="Rules\HasCopyrightHeaderFormattingRule.cs" />
diff --git a/src/Microsoft.DotNet.CodeFormatting/Rules/AttributeNoParenthesesRule.cs b/src/Microsoft.DotNet.CodeFormatting/Rules/AttributeNoParenthesesRule.cs
new file mode 100644
index 00000000..f56bc012
--- /dev/null
+++ b/src/Microsoft.DotNet.CodeFormatting/Rules/AttributeNoParenthesesRule.cs
@@ -0,0 +1,26 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+using System.Linq;
+
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+
+namespace Microsoft.DotNet.CodeFormatting.Rules
+{
+    [SyntaxRuleOrder(SyntaxRuleOrder.AttributeNoParenthesesRule)]
+    internal sealed class AttributeNoParenthesesRule : ISyntaxFormattingRule
+    {
+        public SyntaxNode Process(SyntaxNode syntaxRoot)
+        {
+            var attributes = syntaxRoot.DescendantNodes()
+                                       .OfType<AttributeSyntax>()
+                                       .Where(a => a.ArgumentList != null &&
+                                                   a.ArgumentList.Arguments.Count == 0 &&
+                                                   (!a.ArgumentList.OpenParenToken.IsMissing || !a.ArgumentList.CloseParenToken.IsMissing));
+
+            return syntaxRoot.ReplaceNodes(attributes, (a, n) => a.WithArgumentList(null));
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/Microsoft.DotNet.CodeFormatting/Rules/AttributeSeparateListsRule.cs b/src/Microsoft.DotNet.CodeFormatting/Rules/AttributeSeparateListsRule.cs
new file mode 100644
index 00000000..cc268f02
--- /dev/null
+++ b/src/Microsoft.DotNet.CodeFormatting/Rules/AttributeSeparateListsRule.cs
@@ -0,0 +1,84 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+
+namespace Microsoft.DotNet.CodeFormatting.Rules
+{
+    [SyntaxRuleOrder(SyntaxRuleOrder.AttributeSeparateListsRule)]
+    internal sealed class AttributeSeparateListsRule : ISyntaxFormattingRule
+    {
+        public SyntaxNode Process(SyntaxNode syntaxRoot)
+        {
+            var rewriter = new AttributeListRewriter();
+            return rewriter.Visit(syntaxRoot);
+        }
+
+        private sealed class AttributeListRewriter : CSharpSyntaxRewriter
+        {
+            public override SyntaxNode VisitParameter(ParameterSyntax node)
+            {
+                // We don't want to flatten the attribute lists for parameters. Those are
+                // usually short, such as [In, Out] and collapsing them can actually
+                // improve readability.
+                return node;
+            }
+
+            public override SyntaxList<TNode> VisitList<TNode>(SyntaxList<TNode> list)
+            {
+                list = base.VisitList(list);
+
+                if (typeof (TNode) != typeof (AttributeListSyntax))
+                    return list;
+
+                var attributeLists = (SyntaxList<AttributeListSyntax>) (object) list;
+                return (SyntaxList<TNode>) (object) VisitAttributeLists(attributeLists);
+            }
+
+            private static SyntaxList<AttributeListSyntax> VisitAttributeLists(SyntaxList<AttributeListSyntax> attributeLists)
+            {
+                var result = new List<AttributeListSyntax>();
+
+                foreach (var attributeList in attributeLists)
+                {
+                    var firstIndex = result.Count;
+
+                    for (var i = 0; i < attributeList.Attributes.Count; i++)
+                    {
+                        var attribute = attributeList.Attributes[i];
+                        var separatorTrivia = i < attributeList.Attributes.Count - 1
+                                                ? attributeList.Attributes.GetSeparator(i).GetAllTrivia()
+                                                : Enumerable.Empty<SyntaxTrivia>();
+
+                        var attributeWithoutTrivia = attribute.WithoutLeadingTrivia().WithoutTrailingTrivia();
+                        var singletonList = SyntaxFactory.AttributeList(attributeList.Target, SyntaxFactory.SeparatedList(new[] { attributeWithoutTrivia }))
+                                                         .WithLeadingTrivia(attribute.GetLeadingTrivia())
+                                                         .WithTrailingTrivia(attribute.GetTrailingTrivia().Concat(separatorTrivia));
+                        result.Add(singletonList);
+                    }
+
+                    var lastIndex = result.Count - 1;
+
+                    var leadingTrivia = attributeList.GetLeadingTrivia()
+                                            .Concat(attributeList.OpenBracketToken.TrailingTrivia)
+                                            .Concat(result[firstIndex].GetLeadingTrivia());
+
+                    var trailingTrivia = result[lastIndex].GetTrailingTrivia()
+                                            .Concat(attributeList.CloseBracketToken.LeadingTrivia)
+                                            .Concat(attributeList.GetTrailingTrivia());
+
+                    result[firstIndex] = result[firstIndex].WithLeadingTrivia(leadingTrivia);
+                    result[lastIndex] = result[lastIndex].WithTrailingTrivia(trailingTrivia);
+                }
+
+                return SyntaxFactory.List(result);
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/Microsoft.DotNet.CodeFormatting/Rules/RuleOrder.cs b/src/Microsoft.DotNet.CodeFormatting/Rules/RuleOrder.cs
index 845a3187..2bad211e 100644
--- a/src/Microsoft.DotNet.CodeFormatting/Rules/RuleOrder.cs
+++ b/src/Microsoft.DotNet.CodeFormatting/Rules/RuleOrder.cs
@@ -20,6 +20,8 @@ internal static class SyntaxRuleOrder
         public const int BraceNewLineRule = 6;
         public const int NonAsciiChractersAreEscapedInLiterals = 7;
         public const int TestAssertTrueOrFalseRule = 8;
+        public const int AttributeNoParenthesesRule = 9;
+        public const int AttributeSeparateListsRule = 10;
     }
 
     // Please keep these values sorted by number, not rule name.