diff --git a/.azure/pipelines/ci-public.yml b/.azure/pipelines/ci-public.yml
index 49ea0fdb978b..28ee0c6072bf 100644
--- a/.azure/pipelines/ci-public.yml
+++ b/.azure/pipelines/ci-public.yml
@@ -95,6 +95,7 @@ stages:
   # Code check
   - template: jobs/default-build.yml
     parameters:
+      condition: false # TEMPORARY: Disabled for testing Helix dedup
       jobName: Code_check
       jobDisplayName: Code check
       agentOs: Windows
@@ -110,6 +111,7 @@ stages:
   # Build Windows (x64/x86/arm64)
   - template: jobs/default-build.yml
     parameters:
+      condition: false # TEMPORARY: Disabled for testing Helix dedup
       codeSign: true
       jobName: Windows_build
       jobDisplayName: "Build: Windows x64/x86/arm64"
@@ -229,6 +231,7 @@ stages:
   # Build MacOS arm64
   - template: jobs/default-build.yml
     parameters:
+      condition: false # TEMPORARY: Disabled for testing Helix dedup
       jobName: MacOs_arm64_build
       jobDisplayName: "Build: macOS arm64"
       agentOs: macOs
@@ -260,6 +263,7 @@ stages:
   # Build MacOS x64
   - template: jobs/default-build.yml
     parameters:
+      condition: false # TEMPORARY: Disabled for testing Helix dedup
       jobName: MacOs_x64_build
       jobDisplayName: "Build: macOS x64"
       agentOs: macOs
@@ -290,6 +294,7 @@ stages:
   # Build Linux x64
   - template: jobs/default-build.yml
     parameters:
+      condition: false # TEMPORARY: Disabled for testing Helix dedup
       jobName: Linux_x64_build
       jobDisplayName: "Build: Linux x64"
       agentOs: Linux
@@ -322,6 +327,7 @@ stages:
   # Build Linux ARM
   - template: jobs/default-build.yml
     parameters:
+      condition: false # TEMPORARY: Disabled for testing Helix dedup
       jobName: Linux_arm_build
       jobDisplayName: "Build: Linux ARM"
       agentOs: Linux
@@ -352,6 +358,7 @@ stages:
   # Build Linux ARM64
   - template: jobs/default-build.yml
     parameters:
+      condition: false # TEMPORARY: Disabled for testing Helix dedup
       jobName: Linux_arm64_build
       jobDisplayName: "Build: Linux ARM64"
       agentOs: Linux
@@ -383,6 +390,7 @@ stages:
   # Build Linux Musl x64
   - template: jobs/default-build.yml
     parameters:
+      condition: false # TEMPORARY: Disabled for testing Helix dedup
       jobName: Linux_musl_x64_build
       jobDisplayName: "Build: Linux Musl x64"
       agentOs: Linux
@@ -416,6 +424,7 @@ stages:
   # Build Linux Musl ARM
   - template: jobs/default-build.yml
     parameters:
+      condition: false # TEMPORARY: Disabled for testing Helix dedup
       jobName: Linux_musl_arm_build
       jobDisplayName: "Build: Linux Musl ARM"
       agentOs: Linux
@@ -449,6 +458,7 @@ stages:
   # Build Linux Musl ARM64
   - template: jobs/default-build.yml
     parameters:
+      condition: false # TEMPORARY: Disabled for testing Helix dedup
       jobName: Linux_musl_arm64_build
       jobDisplayName: "Build: Linux Musl ARM64"
       agentOs: Linux
@@ -483,6 +493,7 @@ stages:
     # Test jobs
     - template: jobs/default-build.yml
       parameters:
+        condition: false # TEMPORARY: Disabled for testing Helix dedup
         jobName: Windows_Test
         jobDisplayName: "Test: Windows Server x64"
         agentOs: Windows
@@ -511,6 +522,7 @@ stages:
 
     - template: jobs/default-build.yml
       parameters:
+        condition: false # TEMPORARY: Disabled for testing Helix dedup
         jobName: MacOS_Test
         jobDisplayName: "Test: macOS"
         agentOs: macOS
@@ -532,6 +544,7 @@ stages:
 
     - template: jobs/default-build.yml
       parameters:
+        condition: false # TEMPORARY: Disabled for testing Helix dedup
         jobName: Linux_Test
         jobDisplayName: "Test: Ubuntu x64"
         agentOs: Linux
@@ -553,21 +566,57 @@ stages:
           publishOnError: true
           includeForks: true
 
-    # Helix x64 subset 1
+    # Helix x64 build - shared by both Helix test subsets
     - template: jobs/default-build.yml
       parameters:
-        jobName: Helix_x64_Subset_1
-        jobDisplayName: 'Tests: Helix x64 Subset 1'
+        jobName: Helix_x64_Build
+        jobDisplayName: 'Build: Helix x64'
         agentOs: Windows
-        timeoutInMinutes: 240
+        timeoutInMinutes: 120
         steps:
         # Build the shared framework
         - script: ./eng/build.cmd -ci -prepareMachine -nativeToolsOnMachine -nobl -all -pack -arch x64
                   /p:CrossgenOutput=false /p:ASPNETCORE_TEST_LOG_DIR=artifacts/log $(_InternalRuntimeDownloadArgs)
                   /p:VsTestUseMSBuildOutput=false
           displayName: Build shared fx
-        # -noBuildRepoTasks -noBuildNative -noBuild to avoid repeating work done in the previous step.
-        - script: ./eng/build.cmd -ci -prepareMachine -nativeToolsOnMachine -all -noBuildRepoTasks -noBuildNative -noBuild -test
+        - task: PublishPipelineArtifact@1
+          displayName: Publish Helix build artifacts
+          inputs:
+            targetPath: $(Build.SourcesDirectory)/artifacts
+            artifactName: Helix_Build_Artifacts
+        - task: PublishPipelineArtifact@1
+          displayName: Publish NuGet packages cache
+          inputs:
+            targetPath: $(Build.SourcesDirectory)/.packages
+            artifactName: Helix_NuGet_Packages
+        artifacts:
+        - name: Helix_Build_Logs_Attempt_$(System.JobAttempt)
+          path: artifacts/log/
+          publishOnError: true
+          includeForks: true
+
+    # Helix x64 subset 1
+    - template: jobs/default-build.yml
+      parameters:
+        jobName: Helix_x64_Subset_1
+        jobDisplayName: 'Tests: Helix x64 Subset 1'
+        agentOs: Windows
+        dependsOn: Helix_x64_Build
+        timeoutInMinutes: 240
+        steps:
+        # Download build artifacts from Helix_x64_Build job
+        - task: DownloadPipelineArtifact@2
+          displayName: Download Helix build artifacts
+          inputs:
+            artifact: Helix_Build_Artifacts
+            path: $(Build.SourcesDirectory)/artifacts
+        - task: DownloadPipelineArtifact@2
+          displayName: Download NuGet packages cache
+          inputs:
+            artifact: Helix_NuGet_Packages
+            path: $(Build.SourcesDirectory)/.packages
+        # -noBuildRepoTasks -noBuildNative -noBuild to avoid repeating work done in the build job.
+        - script: ./eng/build.cmd -ci -prepareMachine -nativeToolsOnMachine -restore -all -noBuildRepoTasks -noBuildNative -noBuild -test
                   -projects eng\helix\helix.proj /p:IsHelixPRCheck=true /p:IsHelixJob=true
                   /p:CrossgenOutput=false /p:ASPNETCORE_TEST_LOG_DIR=artifacts/log $(_InternalRuntimeDownloadArgs)
                   /p:VsTestUseMSBuildOutput=false /p:RunTemplateTests=false /p:HelixSubset=1
@@ -588,15 +637,22 @@ stages:
         jobName: Helix_x64_Subset_2
         jobDisplayName: 'Tests: Helix x64 Subset 2'
         agentOs: Windows
+        dependsOn: Helix_x64_Build
         timeoutInMinutes: 240
         steps:
-        # Build the shared framework
-        - script: ./eng/build.cmd -ci -prepareMachine -nativeToolsOnMachine -nobl -all -pack -arch x64
-                  /p:CrossgenOutput=false /p:ASPNETCORE_TEST_LOG_DIR=artifacts/log $(_InternalRuntimeDownloadArgs)
-                  /p:VsTestUseMSBuildOutput=false
-          displayName: Build shared fx
-        # -noBuildRepoTasks -noBuildNative -noBuild to avoid repeating work done in the previous step.
-        - script: ./eng/build.cmd -ci -prepareMachine -nativeToolsOnMachine -all -noBuildRepoTasks -noBuildNative -noBuild -test
+        # Download build artifacts from Helix_x64_Build job
+        - task: DownloadPipelineArtifact@2
+          displayName: Download Helix build artifacts
+          inputs:
+            artifact: Helix_Build_Artifacts
+            path: $(Build.SourcesDirectory)/artifacts
+        - task: DownloadPipelineArtifact@2
+          displayName: Download NuGet packages cache
+          inputs:
+            artifact: Helix_NuGet_Packages
+            path: $(Build.SourcesDirectory)/.packages
+        # -noBuildRepoTasks -noBuildNative -noBuild to avoid repeating work done in the build job.
+        - script: ./eng/build.cmd -ci -prepareMachine -nativeToolsOnMachine -restore -all -noBuildRepoTasks -noBuildNative -noBuild -test
                   -projects eng\helix\helix.proj /p:IsHelixPRCheck=true /p:IsHelixJob=true
                   /p:CrossgenOutput=false /p:ASPNETCORE_TEST_LOG_DIR=artifacts/log $(_InternalRuntimeDownloadArgs)
                   /p:VsTestUseMSBuildOutput=false /p:RunTemplateTests=false /p:HelixSubset=2
@@ -614,6 +670,7 @@ stages:
     # Local development validation
     - template: jobs/default-build.yml
       parameters:
+        condition: false # TEMPORARY: Disabled for testing Helix dedup
         jobName: Local_Windows
         jobDisplayName: 'Test: Windows local development validation'
         agentOs: Windows
@@ -649,12 +706,13 @@ stages:
           publishOnError: true
           includeForks: true
 
-  # Source build
-  - template: /eng/common/templates/job/source-build.yml
-    parameters:
-      platform:
-        name: 'Managed'
-        container: 'mcr.microsoft.com/dotnet-buildtools/prereqs:azurelinux-3.0-net10.0-build-amd64'
+  # Source build - TEMPORARY: Disabled for testing Helix dedup
+  - ${{ if false }}:
+    - template: /eng/common/templates/job/source-build.yml
+      parameters:
+        platform:
+          name: 'Managed'
+          container: 'mcr.microsoft.com/dotnet-buildtools/prereqs:azurelinux-3.0-net10.0-build-amd64'
         buildScript: './eng/build.sh'
         buildArguments: '--source-build $(_InternalRuntimeDownloadArgs)'
         jobProperties:
diff --git a/eng/Build.props b/eng/Build.props
index 764f8847521d..d373055a4bf2 100644
--- a/eng/Build.props
+++ b/eng/Build.props
@@ -270,7 +270,6 @@
                           $(RepoRoot)src\HealthChecks\**\*.csproj;
                           $(RepoRoot)src\Testing\**\*.csproj;
                           $(RepoRoot)src\Grpc\**\*.csproj;
-                          $(RepoRoot)src\ProjectTemplates\**\*.csproj;
                           $(RepoRoot)src\Extensions\**\*.csproj;
                           $(RepoRoot)src\OpenApi\**\*.csproj;
                           $(RepoRoot)src\Validation\**\*.csproj;
diff --git a/src/BuildAfterTargetingPack/BuildAfterTargetingPack.csproj b/src/BuildAfterTargetingPack/BuildAfterTargetingPack.csproj
index 49a8a3b6431e..85c1154ff2f0 100644
--- a/src/BuildAfterTargetingPack/BuildAfterTargetingPack.csproj
+++ b/src/BuildAfterTargetingPack/BuildAfterTargetingPack.csproj
@@ -57,9 +57,14 @@
     <MSBuild Projects="@(RequiresDelayedBuild)" BuildInParallel="$(BuildInParallel)" Targets="Clean" />
   </Target>
 
+  <!--
+    Skip delayed projects when running Helix subset tests. These projects are explicitly excluded from
+    @(ProjectToBuild) via @(RequiresDelayedBuild) -> @(ProjectToExclude), so they shouldn't be included
+    when running subset-based test runs with -noBuild.
+  -->
   <Target Name="CreateHelixPayloadDelayedProjects"
       BeforeTargets="CreateHelixPayload"
-      Condition=" '$(DotNetBuildSourceOnly)' != 'true' AND ('$(TargetOsName)' == 'win' AND '$(TargetArchitecture)' == 'x64') "
+      Condition=" '$(DotNetBuildSourceOnly)' != 'true' AND ('$(TargetOsName)' == 'win' AND '$(TargetArchitecture)' == 'x64') AND '$(HelixSubset)' == '' "
       Returns="@(HelixWorkItem)">
     <MSBuild Projects="@(RequiresDelayedBuild)"
         BuildInParallel="$(BuildInParallel)"
diff --git a/src/Hosting/Hosting/test/Microsoft.AspNetCore.Hosting.Tests.csproj b/src/Hosting/Hosting/test/Microsoft.AspNetCore.Hosting.Tests.csproj
index 866a08e32b43..d42f016fa831 100644
--- a/src/Hosting/Hosting/test/Microsoft.AspNetCore.Hosting.Tests.csproj
+++ b/src/Hosting/Hosting/test/Microsoft.AspNetCore.Hosting.Tests.csproj
@@ -4,6 +4,8 @@
     <TargetFramework>$(DefaultNetCoreTargetFramework)</TargetFramework>
     <!-- EXTEXP0003: MetricCollector is experimental -->
     <NoWarn>$(NoWarn);EXTEXP0003</NoWarn>
+    <!-- Testasset has undeclared dependency on test content in its local directory, which doesn't work on Helix. -->
+    <BuildHelixPayload>false</BuildHelixPayload>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/Middleware/CORS/test/UnitTests/Microsoft.AspNetCore.Cors.Test.csproj b/src/Middleware/CORS/test/UnitTests/Microsoft.AspNetCore.Cors.Test.csproj
index 0d02c5bed4a4..8c4e1718c283 100644
--- a/src/Middleware/CORS/test/UnitTests/Microsoft.AspNetCore.Cors.Test.csproj
+++ b/src/Middleware/CORS/test/UnitTests/Microsoft.AspNetCore.Cors.Test.csproj
@@ -2,6 +2,8 @@
 
   <PropertyGroup>
     <TargetFramework>$(DefaultNetCoreTargetFramework)</TargetFramework>
+    <!-- Testasset has undeclared dependency on test content in its local directory, which doesn't work on Helix. -->
+    <BuildHelixPayload>false</BuildHelixPayload>
   </PropertyGroup>
 
   <ItemGroup>