diff --git a/src/Microsoft.AspNetCore.Razor.Language/DefaultDocumentClassifierPass.cs b/src/Microsoft.AspNetCore.Razor.Language/DefaultDocumentClassifierPass.cs
index 7f9b796e53..303a4411bf 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/DefaultDocumentClassifierPass.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/DefaultDocumentClassifierPass.cs
@@ -8,7 +8,7 @@ namespace Microsoft.AspNetCore.Razor.Language
 {
     internal class DefaultDocumentClassifierPass : DocumentClassifierPassBase
     {
-        public override int Order => RazorIRPass.DefaultFeatureOrder;
+        public override int Order => DefaultFeatureOrder;
 
         protected override string DocumentKind => "default";
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/DefaultInstrumentationPass.cs b/src/Microsoft.AspNetCore.Razor.Language/DefaultInstrumentationPass.cs
index 03c4898cf7..730075b312 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/DefaultInstrumentationPass.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/DefaultInstrumentationPass.cs
@@ -9,7 +9,7 @@ namespace Microsoft.AspNetCore.Razor.Language
 {
     public class DefaultInstrumentationPass : RazorIRPassBase, IRazorIROptimizationPass
     {
-        public override int Order => RazorIRPass.DefaultFeatureOrder;
+        public override int Order => DefaultFeatureOrder;
 
         public override void ExecuteCore(RazorCodeDocument codeDocument, DocumentIRNode irDocument)
         {
diff --git a/src/Microsoft.AspNetCore.Razor.Language/DirectiveRemovalIROptimizationPass.cs b/src/Microsoft.AspNetCore.Razor.Language/DirectiveRemovalIROptimizationPass.cs
index ec9d2b2a5b..b936a8414b 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/DirectiveRemovalIROptimizationPass.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/DirectiveRemovalIROptimizationPass.cs
@@ -8,7 +8,7 @@ namespace Microsoft.AspNetCore.Razor.Language
 {
     internal class DirectiveRemovalIROptimizationPass : RazorIRPassBase, IRazorIROptimizationPass
     {
-        public override int Order => RazorIRPass.DefaultFeatureOrder + 50;
+        public override int Order => DefaultFeatureOrder + 50;
 
         public override void ExecuteCore(RazorCodeDocument codeDocument, DocumentIRNode irDocument)
         {
diff --git a/src/Microsoft.AspNetCore.Razor.Language/DocumentClassifierPassBase.cs b/src/Microsoft.AspNetCore.Razor.Language/DocumentClassifierPassBase.cs
index 7620df1e38..a63996bd3f 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/DocumentClassifierPassBase.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/DocumentClassifierPassBase.cs
@@ -131,7 +131,18 @@ namespace Microsoft.AspNetCore.Razor.Language
 
             public override void VisitUsingStatement(UsingStatementIRNode node)
             {
-                _namespace.AddAfter<UsingStatementIRNode>(node);
+                var children = _namespace.Current.Children;
+                var i = children.Count - 1;
+                for (; i >= 0; i--)
+                {
+                    var child = children[i];
+                    if (child is UsingStatementIRNode)
+                    {
+                        break;
+                    }
+                }
+
+                _namespace.Insert(i + 1, node);
             }
 
             public override void VisitDeclareTagHelperFields(DeclareTagHelperFieldsIRNode node)
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/AddPreallocatedTagHelperHtmlAttributeIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/AddPreallocatedTagHelperHtmlAttributeIRNode.cs
index 44f643d4e0..ff16865838 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/AddPreallocatedTagHelperHtmlAttributeIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/AddPreallocatedTagHelperHtmlAttributeIRNode.cs
@@ -7,7 +7,7 @@ using Microsoft.AspNetCore.Razor.Language.CodeGeneration;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class AddPreallocatedTagHelperHtmlAttributeIRNode : ExtensionIRNode
+    public sealed class AddPreallocatedTagHelperHtmlAttributeIRNode : ExtensionIRNode
     {
         public override IList<RazorIRNode> Children { get; } = EmptyArray;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/AddTagHelperHtmlAttributeIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/AddTagHelperHtmlAttributeIRNode.cs
index 6f206020ca..594378a6a5 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/AddTagHelperHtmlAttributeIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/AddTagHelperHtmlAttributeIRNode.cs
@@ -7,7 +7,7 @@ using Microsoft.AspNetCore.Razor.Language.Legacy;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class AddTagHelperHtmlAttributeIRNode : RazorIRNode
+    public sealed class AddTagHelperHtmlAttributeIRNode : RazorIRNode
     {
         public override ItemCollection Annotations => ReadonlyItemCollection.Empty;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/CSharpAttributeValueIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/CSharpAttributeValueIRNode.cs
index fedafd82fe..4512e75248 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/CSharpAttributeValueIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/CSharpAttributeValueIRNode.cs
@@ -6,7 +6,7 @@ using System.Collections.Generic;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class CSharpAttributeValueIRNode : RazorIRNode
+    public sealed class CSharpAttributeValueIRNode : RazorIRNode
     {
         public override ItemCollection Annotations => ReadonlyItemCollection.Empty;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/CSharpExpressionIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/CSharpExpressionIRNode.cs
index f9197721bb..e8f41f8560 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/CSharpExpressionIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/CSharpExpressionIRNode.cs
@@ -6,7 +6,7 @@ using System.Collections.Generic;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class CSharpExpressionIRNode : RazorIRNode
+    public sealed class CSharpExpressionIRNode : RazorIRNode
     {
         private ItemCollection _annotations;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/CSharpStatementIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/CSharpStatementIRNode.cs
index 5c2a30f369..765ea3dcaf 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/CSharpStatementIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/CSharpStatementIRNode.cs
@@ -6,7 +6,7 @@ using System.Collections.Generic;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class CSharpStatementIRNode : RazorIRNode
+    public sealed class CSharpStatementIRNode : RazorIRNode
     {
         private ItemCollection _annotations;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/ChecksumIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/ChecksumIRNode.cs
index c130eb0884..4622b8e074 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/ChecksumIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/ChecksumIRNode.cs
@@ -7,7 +7,7 @@ using System.Text;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class ChecksumIRNode : RazorIRNode
+    public sealed class ChecksumIRNode : RazorIRNode
     {
         public override ItemCollection Annotations => ReadonlyItemCollection.Empty;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/CreateTagHelperIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/CreateTagHelperIRNode.cs
index 647454a660..707b876c3a 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/CreateTagHelperIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/CreateTagHelperIRNode.cs
@@ -6,7 +6,7 @@ using System.Collections.Generic;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class CreateTagHelperIRNode : RazorIRNode
+    public sealed class CreateTagHelperIRNode : RazorIRNode
     {
         public override ItemCollection Annotations => ReadonlyItemCollection.Empty;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DeclarePreallocatedTagHelperAttributeIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DeclarePreallocatedTagHelperAttributeIRNode.cs
index 0727183265..54a7ef816c 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DeclarePreallocatedTagHelperAttributeIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DeclarePreallocatedTagHelperAttributeIRNode.cs
@@ -8,7 +8,7 @@ using Microsoft.AspNetCore.Razor.Language.Legacy;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class DeclarePreallocatedTagHelperAttributeIRNode : ExtensionIRNode
+    public sealed class DeclarePreallocatedTagHelperAttributeIRNode : ExtensionIRNode
     {
         public override IList<RazorIRNode> Children { get; } = EmptyArray;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DeclarePreallocatedTagHelperHtmlAttributeIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DeclarePreallocatedTagHelperHtmlAttributeIRNode.cs
index 183198c352..0d9ec63849 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DeclarePreallocatedTagHelperHtmlAttributeIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DeclarePreallocatedTagHelperHtmlAttributeIRNode.cs
@@ -8,7 +8,7 @@ using Microsoft.AspNetCore.Razor.Language.Legacy;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class DeclarePreallocatedTagHelperHtmlAttributeIRNode : ExtensionIRNode
+    public sealed class DeclarePreallocatedTagHelperHtmlAttributeIRNode : ExtensionIRNode
     {
         public override IList<RazorIRNode> Children { get; } = EmptyArray;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DeclareTagHelperFieldsIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DeclareTagHelperFieldsIRNode.cs
index 2753b2df45..6cf1b5f609 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DeclareTagHelperFieldsIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DeclareTagHelperFieldsIRNode.cs
@@ -6,7 +6,7 @@ using System.Collections.Generic;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class DeclareTagHelperFieldsIRNode : RazorIRNode
+    public sealed class DeclareTagHelperFieldsIRNode : RazorIRNode
     {
         public override ItemCollection Annotations => ReadonlyItemCollection.Empty;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DesignTimeDirectiveIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DesignTimeDirectiveIRNode.cs
index 8f2a3c19f5..46c8fec9be 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DesignTimeDirectiveIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DesignTimeDirectiveIRNode.cs
@@ -7,7 +7,7 @@ using Microsoft.AspNetCore.Razor.Language.CodeGeneration;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    internal class DesignTimeDirectiveIRNode : ExtensionIRNode
+    internal sealed class DesignTimeDirectiveIRNode : ExtensionIRNode
     {
         public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DirectiveIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DirectiveIRNode.cs
index 2c540c82a7..42033d772e 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DirectiveIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DirectiveIRNode.cs
@@ -7,7 +7,7 @@ using Microsoft.AspNetCore.Razor.Language.Legacy;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class DirectiveIRNode : RazorIRNode
+    public sealed class DirectiveIRNode : RazorIRNode
     {
         private ItemCollection _annotations;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DirectiveTokenIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DirectiveTokenIRNode.cs
index a329569e8c..9bfe6c3152 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DirectiveTokenIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/DirectiveTokenIRNode.cs
@@ -6,7 +6,7 @@ using System.Collections.Generic;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class DirectiveTokenIRNode : RazorIRNode
+    public sealed class DirectiveTokenIRNode : RazorIRNode
     {
         public override ItemCollection Annotations => ReadonlyItemCollection.Empty;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/ExecuteTagHelpersIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/ExecuteTagHelpersIRNode.cs
index 537816efc6..352cc725e8 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/ExecuteTagHelpersIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/ExecuteTagHelpersIRNode.cs
@@ -6,7 +6,7 @@ using System.Collections.Generic;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class ExecuteTagHelpersIRNode : RazorIRNode
+    public sealed class ExecuteTagHelpersIRNode : RazorIRNode
     {
         public override ItemCollection Annotations => ReadonlyItemCollection.Empty;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/HtmlAttributeIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/HtmlAttributeIRNode.cs
index 161e03da31..f71bfae016 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/HtmlAttributeIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/HtmlAttributeIRNode.cs
@@ -6,7 +6,7 @@ using System.Collections.Generic;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class HtmlAttributeIRNode : RazorIRNode
+    public sealed class HtmlAttributeIRNode : RazorIRNode
     {
         public override ItemCollection Annotations => ReadonlyItemCollection.Empty;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/HtmlAttributeValueIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/HtmlAttributeValueIRNode.cs
index b50ba275c2..bd19cb0894 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/HtmlAttributeValueIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/HtmlAttributeValueIRNode.cs
@@ -6,7 +6,7 @@ using System.Collections.Generic;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class HtmlAttributeValueIRNode : RazorIRNode
+    public sealed class HtmlAttributeValueIRNode : RazorIRNode
     {
         public override ItemCollection Annotations => ReadonlyItemCollection.Empty;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/IExtensionIRNodeVisitor`1.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/IExtensionIRNodeVisitor.cs
similarity index 100%
rename from src/Microsoft.AspNetCore.Razor.Language/Intermediate/IExtensionIRNodeVisitor`1.cs
rename to src/Microsoft.AspNetCore.Razor.Language/Intermediate/IExtensionIRNodeVisitor.cs
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/IExtensionIRNodeVisitor`2.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/IExtensionIRNodeVisitor`2.cs
deleted file mode 100644
index f49e30589a..0000000000
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/IExtensionIRNodeVisitor`2.cs
+++ /dev/null
@@ -1,10 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
-
-namespace Microsoft.AspNetCore.Razor.Language.Intermediate
-{
-    public interface IExtensionIRNodeVisitor<TNode, TResult> where TNode : ExtensionIRNode
-    {
-        TResult VisitExtension(TNode node);
-    }
-}
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/NamespaceDeclarationIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/NamespaceDeclarationIRNode.cs
index 9f7945d151..ce61913d58 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/NamespaceDeclarationIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/NamespaceDeclarationIRNode.cs
@@ -6,7 +6,7 @@ using System.Collections.Generic;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class NamespaceDeclarationIRNode : RazorIRNode
+    public sealed class NamespaceDeclarationIRNode : RazorIRNode
     {
         private ItemCollection _annotations;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/RazorIRBuilderExtensions.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/RazorIRBuilderExtensions.cs
deleted file mode 100644
index 502c9f5542..0000000000
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/RazorIRBuilderExtensions.cs
+++ /dev/null
@@ -1,25 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
-
-namespace Microsoft.AspNetCore.Razor.Language.Intermediate
-{
-    public static class RazorIRBuilderExtensions
-    {
-        public static void AddAfter<TNode>(this RazorIRBuilder builder, RazorIRNode node)
-            where TNode : RazorIRNode
-        {
-            var children = builder.Current.Children;
-            var i = children.Count - 1;
-            for (; i >= 0; i--)
-            {
-                var child = children[i];
-                if (child is TNode || child.GetType() == node.GetType())
-                {
-                    break;
-                }
-            }
-
-            builder.Insert(i + 1, node);
-        }
-    }
-}
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/SetPreallocatedTagHelperPropertyIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/SetPreallocatedTagHelperPropertyIRNode.cs
index c07a5d7a0d..fb29f661ed 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/SetPreallocatedTagHelperPropertyIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/SetPreallocatedTagHelperPropertyIRNode.cs
@@ -8,7 +8,7 @@ using Microsoft.AspNetCore.Razor.Language.Legacy;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class SetPreallocatedTagHelperPropertyIRNode : ExtensionIRNode
+    public sealed class SetPreallocatedTagHelperPropertyIRNode : ExtensionIRNode
     {
         public override IList<RazorIRNode> Children { get; } = EmptyArray;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/SetTagHelperPropertyIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/SetTagHelperPropertyIRNode.cs
index 2d5881c421..750860f7a6 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/SetTagHelperPropertyIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/SetTagHelperPropertyIRNode.cs
@@ -7,7 +7,7 @@ using Microsoft.AspNetCore.Razor.Language.Legacy;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class SetTagHelperPropertyIRNode : RazorIRNode
+    public sealed class SetTagHelperPropertyIRNode : RazorIRNode
     {
         public override ItemCollection Annotations => ReadonlyItemCollection.Empty;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/TagHelperIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/TagHelperIRNode.cs
index 6d00bdc0f3..894534ac6b 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/TagHelperIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/TagHelperIRNode.cs
@@ -6,7 +6,7 @@ using System.Collections.Generic;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class TagHelperIRNode : RazorIRNode
+    public sealed class TagHelperIRNode : RazorIRNode
     {
         private ItemCollection _annotations;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/TemplateIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/TemplateIRNode.cs
index dd294f1fbe..52bbbbfb60 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/TemplateIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/TemplateIRNode.cs
@@ -7,7 +7,7 @@ using Microsoft.AspNetCore.Razor.Language.CodeGeneration;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class TemplateIRNode : ExtensionIRNode
+    public sealed class TemplateIRNode : ExtensionIRNode
     {
         public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/UsingStatementIRNode.cs b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/UsingStatementIRNode.cs
index dbc2dc5cca..85bcc51830 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/Intermediate/UsingStatementIRNode.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/Intermediate/UsingStatementIRNode.cs
@@ -6,7 +6,7 @@ using System.Collections.Generic;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public class UsingStatementIRNode : RazorIRNode
+    public sealed class UsingStatementIRNode : RazorIRNode
     {
         public override ItemCollection Annotations => ReadonlyItemCollection.Empty;
 
diff --git a/src/Microsoft.AspNetCore.Razor.Language/RazorIRPass.cs b/src/Microsoft.AspNetCore.Razor.Language/RazorIRPass.cs
deleted file mode 100644
index 63f75d07ff..0000000000
--- a/src/Microsoft.AspNetCore.Razor.Language/RazorIRPass.cs
+++ /dev/null
@@ -1,18 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
-
-namespace Microsoft.AspNetCore.Razor.Language
-{
-    public static class RazorIRPass
-    {
-        /// <summary>
-        /// The default implementation of the <see cref="IRazorEngineFeature"/>s that run in a
-        /// <see cref="IRazorEnginePhase"/> will use this value for its Order property.
-        /// </summary>
-        /// <remarks>
-        /// This value is chosen in such a way that the default implementation runs after the other
-        /// custom <see cref="IRazorEngineFeature"/> implementations for a particular <see cref="IRazorEnginePhase"/>.
-        /// </remarks>
-        public static readonly int DefaultFeatureOrder = 1000;
-    }
-}
diff --git a/src/Microsoft.AspNetCore.Razor.Language/RazorIRPassBase.cs b/src/Microsoft.AspNetCore.Razor.Language/RazorIRPassBase.cs
index 70d287b489..0957fc1471 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/RazorIRPassBase.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/RazorIRPassBase.cs
@@ -8,6 +8,16 @@ namespace Microsoft.AspNetCore.Razor.Language
 {
     public abstract class RazorIRPassBase
     {
+        /// <summary>
+        /// The default implementation of the <see cref="IRazorEngineFeature"/>s that run in a
+        /// <see cref="IRazorEnginePhase"/> will use this value for its Order property.
+        /// </summary>
+        /// <remarks>
+        /// This value is chosen in such a way that the default implementation runs after the other
+        /// custom <see cref="IRazorEngineFeature"/> implementations for a particular <see cref="IRazorEnginePhase"/>.
+        /// </remarks>
+        public static readonly int DefaultFeatureOrder = 1000;
+
         private RazorEngine _engine;
 
         public RazorEngine Engine
diff --git a/src/Microsoft.AspNetCore.Razor.Language/RazorPreallocatedTagHelperAttributeOptimizationPass.cs b/src/Microsoft.AspNetCore.Razor.Language/RazorPreallocatedTagHelperAttributeOptimizationPass.cs
index c1b5528b56..18cb8ddae6 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/RazorPreallocatedTagHelperAttributeOptimizationPass.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/RazorPreallocatedTagHelperAttributeOptimizationPass.cs
@@ -10,7 +10,7 @@ namespace Microsoft.AspNetCore.Razor.Language
 {
     internal class RazorPreallocatedTagHelperAttributeOptimizationPass : RazorIRPassBase, IRazorIROptimizationPass
     {
-        public override int Order => RazorIRPass.DefaultFeatureOrder;
+        public override int Order => DefaultFeatureOrder;
 
         public override void ExecuteCore(RazorCodeDocument codeDocument, DocumentIRNode irDocument)
         {
diff --git a/test/Microsoft.AspNetCore.Razor.Language.Test/DocumentClassifierPassBaseTest.cs b/test/Microsoft.AspNetCore.Razor.Language.Test/DocumentClassifierPassBaseTest.cs
index 92305bad3d..bfc18d9460 100644
--- a/test/Microsoft.AspNetCore.Razor.Language.Test/DocumentClassifierPassBaseTest.cs
+++ b/test/Microsoft.AspNetCore.Razor.Language.Test/DocumentClassifierPassBaseTest.cs
@@ -296,7 +296,7 @@ namespace Microsoft.AspNetCore.Razor.Language
 
         private class TestDocumentClassifierPass : DocumentClassifierPassBase
         {
-            public override int Order => RazorIRPass.DefaultFeatureOrder;
+            public override int Order => RazorIRPassBase.DefaultFeatureOrder;
 
             public bool ShouldMatch { get; set; } = true;
 
diff --git a/test/Microsoft.AspNetCore.Razor.Language.Test/Intermediate/RazorIRBuilderExtensionsTest.cs b/test/Microsoft.AspNetCore.Razor.Language.Test/Intermediate/RazorIRBuilderExtensionsTest.cs
deleted file mode 100644
index 2e5b2ef4f5..0000000000
--- a/test/Microsoft.AspNetCore.Razor.Language.Test/Intermediate/RazorIRBuilderExtensionsTest.cs
+++ /dev/null
@@ -1,123 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
-
-using System;
-using System.Collections.Generic;
-using Microsoft.AspNetCore.Razor.Language.Legacy;
-using Microsoft.AspNetCore.Testing;
-using Xunit;
-
-namespace Microsoft.AspNetCore.Razor.Language.Intermediate
-{
-    public class RazorIRBuilderExtensionsTest
-    {
-        [Fact]
-        public void AddAfter_EmptyList()
-        {
-            // Arrange
-            var builder = RazorIRBuilder.Document();
-
-            var node = new BasicIRNode3();
-
-            // Act
-            builder.AddAfter<BasicIRNode>(node);
-
-            // Assert
-            Assert.Collection(builder.Current.Children, n => Assert.Same(node, n));
-        }
-
-        [Fact]
-        public void AddAfter_AfterMatch()
-        {
-            // Arrange
-            var builder = RazorIRBuilder.Document();
-            builder.Add(new BasicIRNode());
-            builder.Add(new BasicIRNode());
-            builder.Add(new BasicIRNode3());
-
-            var node = new BasicIRNode3();
-
-            // Act
-            builder.AddAfter<BasicIRNode>(node);
-
-            // Assert
-            Assert.Collection(
-                builder.Current.Children,
-                n => Assert.IsType<BasicIRNode>(n),
-                n => Assert.IsType<BasicIRNode>(n),
-                n => Assert.IsType<BasicIRNode3>(n),
-                n => Assert.Same(node, n));
-        }
-
-        [Fact]
-        public void AddAfter_AfterMatch_Noncontinuous()
-        {
-            // Arrange
-            var builder = RazorIRBuilder.Document();
-            builder.Add(new BasicIRNode());
-            builder.Add(new BasicIRNode2());
-            builder.Add(new BasicIRNode());
-
-            var node = new BasicIRNode3();
-
-            // Act
-            builder.AddAfter<BasicIRNode>(node);
-
-            // Assert
-            Assert.Collection(
-                builder.Current.Children,
-                n => Assert.IsType<BasicIRNode>(n),
-                n => Assert.IsType<BasicIRNode2>(n),
-                n => Assert.IsType<BasicIRNode>(n),
-                n => Assert.Same(node, n));
-        }
-
-        private class BasicIRNode : RazorIRNode
-        {
-            public override ItemCollection Annotations { get; } = new DefaultItemCollection();
-
-            public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
-
-            public override RazorIRNode Parent { get; set; }
-
-            public override SourceSpan? Source { get; set; }
-
-            public override void Accept(RazorIRNodeVisitor visitor)
-            {
-                throw new NotImplementedException();
-            }
-        }
-
-        private class BasicIRNode2 : RazorIRNode
-        {
-            public override ItemCollection Annotations { get; } = new DefaultItemCollection();
-
-            public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
-
-            public override RazorIRNode Parent { get; set; }
-
-            public override SourceSpan? Source { get; set; }
-
-            public override void Accept(RazorIRNodeVisitor visitor)
-            {
-                throw new NotImplementedException();
-            }
-        }
-
-        private class BasicIRNode3 : RazorIRNode
-        {
-            public override ItemCollection Annotations { get; } = new DefaultItemCollection();
-
-            public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
-
-            public override RazorIRNode Parent { get; set; }
-
-            public override SourceSpan? Source { get; set; }
-
-            public override void Accept(RazorIRNodeVisitor visitor)
-            {
-                throw new NotImplementedException();
-            }
-        }
-    }
-}