diff --git a/src/Microsoft.AspNetCore.Razor.Language/AssemblyExtension.cs b/src/Microsoft.AspNetCore.Razor.Language/AssemblyExtension.cs
index b93323e018..83b70cd7aa 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/AssemblyExtension.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/AssemblyExtension.cs
@@ -27,5 +27,29 @@ namespace Microsoft.AspNetCore.Razor.Language
         public override string ExtensionName { get; }
 
         public Assembly Assembly { get; }
+
+        public RazorExtensionInitializer CreateInitializer()
+        {
+            // It's not an error to have an assembly with no initializers. This is useful to specify a dependency
+            // that doesn't really provide any Razor configuration.
+            var attributes = Assembly.GetCustomAttributes<ProvideRazorExtensionInitializerAttribute>();
+            foreach (var attribute in attributes)
+            {
+                // Using extension names and requiring them to line up allows a single assembly to ship multiple
+                // extensions/initializers for different configurations.
+                if (!string.Equals(attribute.ExtensionName, ExtensionName, StringComparison.Ordinal))
+                {
+                    continue;
+                }
+
+                // There's no real protection/exception handling here because this set isn't really user-extensible
+                // right now. This would be a great place to add some additional diagnostics and hardening in the
+                // future.
+                var initializer = (RazorExtensionInitializer)Activator.CreateInstance(attribute.InitializerType);
+                return initializer;
+            }
+
+            return null;
+        }
     }
 }
diff --git a/src/Microsoft.AspNetCore.Razor.Language/RazorProjectEngine.cs b/src/Microsoft.AspNetCore.Razor.Language/RazorProjectEngine.cs
index e76bdffc94..341be49296 100644
--- a/src/Microsoft.AspNetCore.Razor.Language/RazorProjectEngine.cs
+++ b/src/Microsoft.AspNetCore.Razor.Language/RazorProjectEngine.cs
@@ -159,29 +159,8 @@ namespace Microsoft.AspNetCore.Razor.Language
                 // lid on how things work until we add official support for extensibility everywhere. So, this is
                 // intentionally inflexible for the time being.
                 var extension = extensions[i] as AssemblyExtension;
-                if (extension == null)
-                {
-                    continue;
-                }
-
-                // It's not an error to have an assembly with no initializers. This is useful to specify a dependency
-                // that doesn't really provide any Razor configuration.
-                var attributes = extension.Assembly.GetCustomAttributes<ProvideRazorExtensionInitializerAttribute>();
-                foreach (var attribute in attributes)
-                {
-                    // Using extension names and requiring them to line up allows a single assembly to ship multiple
-                    // extensions/initializers for different configurations.
-                    if (!string.Equals(attribute.ExtensionName, extension.ExtensionName, StringComparison.Ordinal))
-                    {
-                        continue;
-                    }
-
-                    // There's no real protection/exception handling here because this set isn't really user-extensible
-                    // right now. This would be a great place to add some additional diagnostics and hardening in the
-                    // future.
-                    var initializer = (RazorExtensionInitializer)Activator.CreateInstance(attribute.InitializerType);
-                    initializer.Initialize(builder);
-                }
+                var initializer = extension?.CreateInitializer();
+                initializer?.Initialize(builder);
             }
         }
     }
diff --git a/src/Microsoft.CodeAnalysis.Razor.Workspaces/ExportCustomProjectEngineFactoryAttribute.cs b/src/Microsoft.CodeAnalysis.Razor.Workspaces/ExportCustomProjectEngineFactoryAttribute.cs
new file mode 100644
index 0000000000..923cb0a66e
--- /dev/null
+++ b/src/Microsoft.CodeAnalysis.Razor.Workspaces/ExportCustomProjectEngineFactoryAttribute.cs
@@ -0,0 +1,28 @@
+// 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.Composition;
+
+namespace Microsoft.CodeAnalysis.Razor
+{
+    [MetadataAttribute]
+    [AttributeUsage(AttributeTargets.Class, AllowMultiple = false, Inherited = true)]
+    public class ExportCustomProjectEngineFactoryAttribute : ExportAttribute, ICustomProjectEngineFactoryMetadata
+    {
+        public ExportCustomProjectEngineFactoryAttribute(string configurationName)
+            : base(typeof(IProjectEngineFactory))
+        {
+            if (configurationName == null)
+            {
+                throw new ArgumentNullException(nameof(configurationName));
+            }
+
+            ConfigurationName = configurationName;
+        }
+
+        public string ConfigurationName { get; }
+
+        public bool SupportsSerialization { get; set; }
+    }
+}
diff --git a/src/Microsoft.CodeAnalysis.Razor.Workspaces/ICustomProjectEngineFactoryMetadata.cs b/src/Microsoft.CodeAnalysis.Razor.Workspaces/ICustomProjectEngineFactoryMetadata.cs
new file mode 100644
index 0000000000..3f93a6e605
--- /dev/null
+++ b/src/Microsoft.CodeAnalysis.Razor.Workspaces/ICustomProjectEngineFactoryMetadata.cs
@@ -0,0 +1,12 @@
+// 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.CodeAnalysis.Razor
+{
+    public interface ICustomProjectEngineFactoryMetadata
+    {
+        string ConfigurationName { get; }
+
+        bool SupportsSerialization { get; }
+    }
+}
diff --git a/src/Microsoft.CodeAnalysis.Razor.Workspaces/IProjectEngineFactory.cs b/src/Microsoft.CodeAnalysis.Razor.Workspaces/IProjectEngineFactory.cs
new file mode 100644
index 0000000000..903c47842b
--- /dev/null
+++ b/src/Microsoft.CodeAnalysis.Razor.Workspaces/IProjectEngineFactory.cs
@@ -0,0 +1,13 @@
+// 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 Microsoft.AspNetCore.Razor.Language;
+
+namespace Microsoft.CodeAnalysis.Razor
+{
+    public interface IProjectEngineFactory
+    {
+        RazorProjectEngine Create(RazorConfiguration configuration, RazorProjectFileSystem fileSystem, Action<RazorProjectEngineBuilder> configure);
+    }
+}