diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Tools/src/GenerateCommand.cs b/src/Razor/Microsoft.AspNetCore.Razor.Tools/src/GenerateCommand.cs
index 6bcf622d1ddb..658b9d22631d 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Tools/src/GenerateCommand.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Tools/src/GenerateCommand.cs
@@ -201,6 +201,7 @@ private int ExecuteCore(
                 if (GenerateDeclaration.HasValue())
                 {
                     b.Features.Add(new SetSuppressPrimaryMethodBodyOptionFeature());
+                    b.Features.Add(new SuppressChecksumOptionsFeature());
                 }
 
                 if (RootNamespace.HasValue())
@@ -227,6 +228,7 @@ private int ExecuteCore(
             });
 
             var results = GenerateCode(engine, sourceItems);
+            var isGeneratingDeclaration = GenerateDeclaration.HasValue();
 
             foreach (var result in results)
             {
@@ -255,6 +257,18 @@ private int ExecuteCore(
                 {
                     // Only output the file if we generated it without errors.
                     var outputFilePath = result.InputItem.OutputPath;
+                    var generatedCode = result.CSharpDocument.GeneratedCode;
+                    if (isGeneratingDeclaration)
+                    {
+                        // When emiting declarations, only write if it the contents are different.
+                        // This allows build incrementalism to kick in when the declaration remains unchanged between builds.
+                        if (File.Exists(outputFilePath) &&
+                            string.Equals(File.ReadAllText(outputFilePath), generatedCode, StringComparison.Ordinal))
+                        {
+                            continue;
+                        }
+                    }
+
                     File.WriteAllText(outputFilePath, result.CSharpDocument.GeneratedCode);
                 }
             }
diff --git a/src/Razor/Microsoft.NET.Sdk.Razor/integrationtests/BuildIncrementalismTest.cs b/src/Razor/Microsoft.NET.Sdk.Razor/integrationtests/BuildIncrementalismTest.cs
index df84c3b7a66b..e651cad69f80 100644
--- a/src/Razor/Microsoft.NET.Sdk.Razor/integrationtests/BuildIncrementalismTest.cs
+++ b/src/Razor/Microsoft.NET.Sdk.Razor/integrationtests/BuildIncrementalismTest.cs
@@ -172,11 +172,61 @@ async Task VerifyError()
             }
         }
 
+        [Fact]
+        [InitializeTestProject("MvcWithComponents")]
+        public async Task BuildComponents_DoesNotRegenerateComponentDefinition_WhenDefinitionIsUnchanged()
+        {
+            // Act - 1
+            var updatedContent = "Some content";
+            var tagHelperOutputCache = Path.Combine(IntermediateOutputPath, "MvcWithComponents.TagHelpers.output.cache");
+
+            var generatedFile = Path.Combine(RazorIntermediateOutputPath, "Views", "Shared", "NavMenu.razor.g.cs");
+            var generatedDefinitionFile = Path.Combine(RazorComponentIntermediateOutputPath, "Views", "Shared", "NavMenu.razor.g.cs");
+
+            // Assert - 1
+            var result = await DotnetMSBuild("Build");
+
+            Assert.BuildPassed(result);
+            var outputFile = Path.Combine(OutputPath, "MvcWithComponents.dll");
+            Assert.FileExists(result, OutputPath, "MvcWithComponents.dll");
+            var outputAssemblyThumbprint = GetThumbPrint(outputFile);
+
+            Assert.FileExists(result, generatedDefinitionFile);
+            var generatedDefinitionThumbprint = GetThumbPrint(generatedDefinitionFile);
+            Assert.FileExists(result, generatedFile);
+            var generatedFileThumbprint = GetThumbPrint(generatedFile);
+
+            Assert.FileExists(result, tagHelperOutputCache);
+            Assert.FileContains(
+                result,
+                tagHelperOutputCache,
+                @"""Name"":""MvcWithComponents.Views.Shared.NavMenu""");
+
+            var definitionThumbprint = GetThumbPrint(tagHelperOutputCache);
+
+            // Act - 2
+            ReplaceContent(updatedContent, "Views", "Shared", "NavMenu.razor");
+            result = await DotnetMSBuild("Build");
+
+            // Assert - 2
+            Assert.FileExists(result, generatedDefinitionFile);
+            // Definition file remains unchanged.
+            Assert.Equal(generatedDefinitionThumbprint, GetThumbPrint(generatedDefinitionFile));
+            Assert.FileExists(result, generatedFile);
+            // Generated file should change and include the new content.
+            Assert.NotEqual(generatedFileThumbprint, GetThumbPrint(generatedFile));
+            Assert.FileContains(result, generatedFile, updatedContent);
+
+            // TagHelper cache should remain unchanged.
+            Assert.Equal(definitionThumbprint, GetThumbPrint(tagHelperOutputCache));
+        }
+
         [Fact]
         [InitializeTestProject("MvcWithComponents")]
         public async Task BuildComponents_RegeneratesComponentDefinition_WhenFilesChange()
         {
             // Act - 1
+            var updatedContent = "@code { [Parameter] public string AParameter { get; set; } }";
             var tagHelperOutputCache = Path.Combine(IntermediateOutputPath, "MvcWithComponents.TagHelpers.output.cache");
 
             var generatedFile = Path.Combine(RazorIntermediateOutputPath, "Views", "Shared", "NavMenu.razor.g.cs");
@@ -204,7 +254,7 @@ public async Task BuildComponents_RegeneratesComponentDefinition_WhenFilesChange
             var definitionThumbprint = GetThumbPrint(tagHelperOutputCache);
 
             // Act - 2
-            ReplaceContent("Different things", "Views", "Shared", "NavMenu.razor");
+            ReplaceContent(updatedContent, "Views", "Shared", "NavMenu.razor");
             result = await DotnetMSBuild("Build");
 
             // Assert - 2
@@ -222,8 +272,12 @@ public async Task BuildComponents_RegeneratesComponentDefinition_WhenFilesChange
                 tagHelperOutputCache,
                 @"""Name"":""MvcWithComponents.Views.Shared.NavMenu""");
 
-            // TODO:
-            Assert.Equal(definitionThumbprint, GetThumbPrint(tagHelperOutputCache));
+            Assert.FileContains(
+                result,
+                tagHelperOutputCache,
+                "AParameter");
+
+            Assert.NotEqual(definitionThumbprint, GetThumbPrint(tagHelperOutputCache));
         }
 
         [Fact]
diff --git a/src/Razor/Microsoft.NET.Sdk.Razor/src/build/netstandard2.0/Microsoft.NET.Sdk.Razor.Component.targets b/src/Razor/Microsoft.NET.Sdk.Razor/src/build/netstandard2.0/Microsoft.NET.Sdk.Razor.Component.targets
index 89e93a3a98a4..922d3fb34ef2 100644
--- a/src/Razor/Microsoft.NET.Sdk.Razor/src/build/netstandard2.0/Microsoft.NET.Sdk.Razor.Component.targets
+++ b/src/Razor/Microsoft.NET.Sdk.Razor/src/build/netstandard2.0/Microsoft.NET.Sdk.Razor.Component.targets
@@ -29,6 +29,7 @@ Copyright (c) .NET Foundation. All rights reserved.
     <!-- Used for tracking inputs to component generation -->
     <_RazorComponentInputHash></_RazorComponentInputHash>
     <_RazorComponentInputCacheFile>$(IntermediateOutputPath)$(MSBuildProjectName).RazorComponent.input.cache</_RazorComponentInputCacheFile>
+    <_RazorComponentDeclarationOutputCacheFile>$(IntermediateOutputPath)$(MSBuildProjectName).RazorComponent.output.cache</_RazorComponentDeclarationOutputCacheFile>
   </PropertyGroup>
 
   <ItemGroup>
@@ -85,7 +86,7 @@ Copyright (c) .NET Foundation. All rights reserved.
     Name="RazorGenerateComponentDeclaration"
     DependsOnTargets="$(RazorGenerateComponentDeclarationDependsOn)"
     Inputs="$(MSBuildAllProjects);@(RazorComponentWithTargetPath);$(_RazorComponentInputCacheFile)"
-    Outputs="@(_RazorComponentDeclaration)"
+    Outputs="$(_RazorComponentDeclarationOutputCacheFile)"
     Condition="'@(RazorComponentWithTargetPath->Count())'!='0'">
 
     <ItemGroup>
@@ -120,8 +121,13 @@ Copyright (c) .NET Foundation. All rights reserved.
       TagHelperManifest="$(_RazorComponentDeclarationManifest)"
       GenerateDeclaration="true" />
 
+    <Touch
+      Files="$(_RazorComponentDeclarationOutputCacheFile)"
+      AlwaysCreate="true" />
+
     <ItemGroup>
       <FileWrites Include="@(_RazorComponentDeclaration)" />
+      <FileWrites Include="$(_RazorComponentDeclarationOutputCacheFile)" />
     </ItemGroup>
   </Target>