diff --git a/eng/Versions.props b/eng/Versions.props
index 6b7a1c221b31a3..f1f70bf2609096 100644
--- a/eng/Versions.props
+++ b/eng/Versions.props
@@ -50,14 +50,15 @@
     <MicrosoftDotNetPlatformAbstractionsVersion>3.0.0</MicrosoftDotNetPlatformAbstractionsVersion>
     <!-- CoreClr dependencies -->
     <MicrosoftNETCoreILAsmVersion>5.0.0-alpha1.19552.2</MicrosoftNETCoreILAsmVersion>
-    <MicrosoftNETCoreRuntimeCoreCLRVersion>5.0.0-alpha1.19551.1</MicrosoftNETCoreRuntimeCoreCLRVersion>
-    <MicrosoftNETSdkILVersion>5.0.0-alpha1.19551.1</MicrosoftNETSdkILVersion>
+    <MicrosoftNETCoreRuntimeCoreCLRVersion>5.0.0-alpha1.19525.1</MicrosoftNETCoreRuntimeCoreCLRVersion>
+    <MicrosoftNETSdkILVersion>5.0.0-alpha1.19552.2</MicrosoftNETSdkILVersion>
     <!-- Libraries dependencies -->
     <MicrosoftNETCorePlatformsVersion>5.0.0-alpha.1.19551.5</MicrosoftNETCorePlatformsVersion>
     <MicrosoftPrivateCoreFxNETCoreAppVersion>5.0.0-alpha.1.19551.5</MicrosoftPrivateCoreFxNETCoreAppVersion>
     <MicrosoftNETCoreTargetsVersion>5.0.0-alpha.1.19551.5</MicrosoftNETCoreTargetsVersion>
     <SystemTextJsonVersion>5.0.0-alpha.1.19551.5</SystemTextJsonVersion>
     <SystemTextEncodingsWebVersion>5.0.0-alpha.1.19551.5</SystemTextEncodingsWebVersion>
+     <runtimenativeSystemIOPortsVersion>5.0.0-alpha.1.19551.5</runtimenativeSystemIOPortsVersion>
     <!-- Standard dependencies -->
     <NETStandardLibraryVersion>2.2.0-prerelease.19551.1</NETStandardLibraryVersion>
     <!-- dotnet-optimization dependencies -->
diff --git a/eng/pipelines/libraries/.azure-ci.yml b/eng/pipelines/libraries/.azure-ci.yml
index cbbe053e478898..2300420a24e80e 100644
--- a/eng/pipelines/libraries/.azure-ci.yml
+++ b/eng/pipelines/libraries/.azure-ci.yml
@@ -7,10 +7,9 @@ trigger:
   branches:
     include:
     - master
-    - release/3.*
   paths:
     exclude:
-    - Documentation/*
+    - docs/*
     - CODE-OF-CONDUCT.md
     - CONTRIBUTING.md
     - LICENSE.TXT
@@ -18,15 +17,16 @@ trigger:
     - README.md
     - SECURITY.md
     - THIRD-PARTY-NOTICES.TXT
+    - src/installer/*
+    - src/coreclr/*
 
 pr:
   branches:
     include:
     - master
-    - release/3.*
   paths:
     exclude:
-    - Documentation/*
+    - docs/*
     - CODE-OF-CONDUCT.md
     - CONTRIBUTING.md
     - LICENSE.TXT
@@ -34,6 +34,8 @@ pr:
     - README.md
     - SECURITY.md
     - THIRD-PARTY-NOTICES.TXT
+    - src/installer/*
+    - src/coreclr/*
 
 resources:
   containers:
@@ -73,32 +75,32 @@ variables:
 
 stages:
   # Windows legs
-  - template: /eng/pipelines/windows.yml
+  - template: /eng/pipelines/libraries/windows.yml
     parameters:
       isOfficialBuild: ${{ and(ne(variables['System.TeamProject'], 'public'), notIn(variables['Build.Reason'], 'PullRequest')) }}
       fullMatrix: ${{ notIn(variables['Build.Reason'], 'PullRequest') }}
 
   # Linux legs
-  - template: /eng/pipelines/linux.yml
+  - template: /eng/pipelines/libraries/linux.yml
     parameters:
       isOfficialBuild: ${{ and(ne(variables['System.TeamProject'], 'public'), notIn(variables['Build.Reason'], 'PullRequest')) }}
       fullMatrix: ${{ notIn(variables['Build.Reason'], 'PullRequest') }}
 
   # MacOS legs
-  - template: /eng/pipelines/macos.yml
+  - template: /eng/pipelines/libraries/macos.yml
     parameters:
       isOfficialBuild: ${{ and(ne(variables['System.TeamProject'], 'public'), notIn(variables['Build.Reason'], 'PullRequest')) }}
       fullMatrix: ${{ notIn(variables['Build.Reason'], 'PullRequest') }}
 
     # FreeBSD leg is only for official builds
-    # - template: /eng/pipelines/freebsd.yml
+    # - template: /eng/pipelines/libraries/freebsd.yml
     #   parameters:
     #     isOfficialBuild: ${{ and(ne(variables['System.TeamProject'], 'public'), notIn(variables['Build.Reason'], 'PullRequest')) }}
     #     fullMatrix: ${{ notIn(variables['Build.Reason'], 'PullRequest') }}
 
   # Publish and validation steps. Only run in official builds
   - ${{ if and(ne(variables['System.TeamProject'], 'public'), notIn(variables['Build.Reason'], 'PullRequest')) }}:
-    - template: /eng/pipelines/pre-publish.yml
+    - template: /eng/pipelines/libraries/pre-publish.yml
       parameters:
         dependsOn:
           - WindowsStage
diff --git a/eng/pipelines/libraries/corefx-base.yml b/eng/pipelines/libraries/corefx-base.yml
index 3080cb58d552ff..961d3b39677543 100644
--- a/eng/pipelines/libraries/corefx-base.yml
+++ b/eng/pipelines/libraries/corefx-base.yml
@@ -32,10 +32,10 @@ parameters:
   # Required: submitToHelix -> Boolean -> Value to know if it should submit tests payloads to helix.
 
   # Optional: buildScriptPrefix -> String -> string to append to Unix build script.
-  #   buildScriptPrefix: 'HOME=/home/ ' -> 'HOME=/home/ ./build.sh ...'
+  #   buildScriptPrefix: 'HOME=/home/ ' -> 'HOME=/home/ ./libraries.sh ...'
 
   # Optional: buildExtraArguments -> String -> string to append at the end of the build arguments
-  #   buildExtraArguments: /p:RuntimeOS=win10 -> 'build.cmd ... /p:RuntimeOS=win10'
+  #   buildExtraArguments: /p:RuntimeOS=win10 -> 'libraries.cmd ... /p:RuntimeOS=win10'
 
   # Optional: customBuildSteps -> Array -> list of steps to run instead of the common build steps.
   #   customBuildSteps:
@@ -52,7 +52,7 @@ parameters:
 
 jobs:
   - ${{ each job in parameters.jobs }}:
-    - template: ../common/templates/job/job.yml
+    - template: /eng/common/templates/job/job.yml
       parameters:
         variables:
 
@@ -96,12 +96,12 @@ jobs:
 
         # Windows variables
         - ${{ if eq(parameters.targetOS, 'Windows_NT') }}:
-          - _buildScript: build.cmd
+          - _buildScript: libraries.cmd
           - _msbuildCommand: powershell -ExecutionPolicy ByPass -NoProfile eng\common\msbuild.ps1 -warnaserror:0 -ci
 
         # Non-Windows variables
         - ${{ if ne(parameters.targetOS, 'Windows_NT') }}:
-          - _buildScript: ${{ job.buildScriptPrefix }}./build.sh
+          - _buildScript: ${{ job.buildScriptPrefix }}./libraries.sh
           - _msbuildCommand: ${{ job.buildScriptPrefix }}./eng/common/msbuild.sh --warnaserror false --ci
           - ${{ if eq(parameters.isOfficialBuild, 'true') }}:
             - _commonArguments: $(_args) -stripSymbols
@@ -186,7 +186,7 @@ jobs:
                   artifactType: container
                 condition: and(succeeded(), eq(variables['_publishTests'], 'true'))
 
-            - template: /eng/pipelines/helix.yml
+            - template: /eng/pipelines/libraries/helix.yml
               parameters:
                 # send tests to helix only on public builds, official scheduled builds or manual official builds.
                 condition: eq(${{ parameters.isOfficialBuild }}, False)
diff --git a/eng/pipelines/libraries/helix.yml b/eng/pipelines/libraries/helix.yml
index 419df576489ae5..916f86e843de9c 100644
--- a/eng/pipelines/libraries/helix.yml
+++ b/eng/pipelines/libraries/helix.yml
@@ -13,7 +13,7 @@ parameters:
 
 steps:
   - script: ${{ parameters.msbuildScript }}
-            src/sendtohelix.proj
+            src/libraries/sendtohelix.proj
             /t:test
             /p:ArchGroup=${{ parameters.archGroup }}
             /p:ConfigurationGroup=${{ parameters.configuration }}
diff --git a/eng/pipelines/libraries/outerloop.yml b/eng/pipelines/libraries/outerloop.yml
index 00c22ed477b6cf..a43057bbd298da 100644
--- a/eng/pipelines/libraries/outerloop.yml
+++ b/eng/pipelines/libraries/outerloop.yml
@@ -31,7 +31,7 @@ resources:
 stages:
   # Windows outerloop legs
   - ${{ if or(endsWith(variables['Build.DefinitionName'], 'windows'), endsWith(variables['Build.DefinitionName'], 'outerloop')) }}:
-    - template: /eng/pipelines/windows.yml
+    - template: /eng/pipelines/libraries/windows.yml
       parameters:
         isOfficialBuild: ${{ and(ne(variables['System.TeamProject'], 'public'), notIn(variables['Build.Reason'], 'PullRequest')) }}
         fullMatrix: ${{ notIn(variables['Build.Reason'], 'PullRequest') }}
@@ -39,7 +39,7 @@ stages:
 
   # Linux outerloop legs
   - ${{ if or(endsWith(variables['Build.DefinitionName'], 'linux'), endsWith(variables['Build.DefinitionName'], 'outerloop')) }}:
-    - template: /eng/pipelines/linux.yml
+    - template: /eng/pipelines/libraries/linux.yml
       parameters:
         isOfficialBuild: ${{ and(ne(variables['System.TeamProject'], 'public'), notIn(variables['Build.Reason'], 'PullRequest')) }}
         fullMatrix: ${{ notIn(variables['Build.Reason'], 'PullRequest') }}
@@ -47,7 +47,7 @@ stages:
 
   # MacOS outerloop legs
   - ${{ if or(endsWith(variables['Build.DefinitionName'], 'osx'), endsWith(variables['Build.DefinitionName'], 'outerloop')) }}:
-    - template: /eng/pipelines/macos.yml
+    - template: /eng/pipelines/libraries/macos.yml
       parameters:
         isOfficialBuild: ${{ and(ne(variables['System.TeamProject'], 'public'), notIn(variables['Build.Reason'], 'PullRequest')) }}
         fullMatrix: ${{ notIn(variables['Build.Reason'], 'PullRequest') }}
diff --git a/eng/pipelines/libraries/pre-publish.yml b/eng/pipelines/libraries/pre-publish.yml
index 9d0460bd01ee11..c05b46d281dbdf 100644
--- a/eng/pipelines/libraries/pre-publish.yml
+++ b/eng/pipelines/libraries/pre-publish.yml
@@ -7,7 +7,7 @@ stages:
   displayName: Pre-publish
   dependsOn: ${{ parameters.dependsOn }}
   jobs:
-    - template: ../common/templates/jobs/jobs.yml
+    - template: /eng/common/templates/jobs/jobs.yml
       parameters:
         enableMicrobuild: true
         enablePublishUsingPipelines: $(_PublishUsingPipelines)
@@ -51,12 +51,12 @@ stages:
                 artifactName: packages
                 downloadPath: $(_artifactsDir)
 
-            - script: build.cmd
+            - script: libraries.cmd
                       -restore
                       -ci
               displayName: Restore tools
 
-            - script: build.cmd
+            - script: libraries.cmd
                       -sign
                       -ci
                       -configuration $(_BuildConfig)
@@ -64,7 +64,7 @@ stages:
                       /p:OfficialBuildId=$(Build.BuildNumber)
               displayName: Sign packages
 
-            - script: build.cmd
+            - script: libraries.cmd
                       -publish
                       -ci
                       -configuration $(_BuildConfig)
@@ -77,7 +77,7 @@ stages:
                       /bl:$(Build.SourcesDirectory)/artifacts/log/$(_BuildConfig)/PublishToArtifacts.binlog
               displayName: Publish to artifacts and produce manifest
 
-            - script: powershell -ExecutionPolicy ByPass -NoProfile eng\common\msbuild.ps1 src\build.proj
+            - script: powershell -ExecutionPolicy ByPass -NoProfile eng\common\msbuild.ps1 src\libraries\build.proj
                       -warnaserror:0 -ci
                       /t:UpdatePublishedVersions
                       /p:GitHubAuthToken=$(AccessToken-dotnet-build-bot-public-repo)
diff --git a/eng/pipelines/libraries/stress/http-windows.yml b/eng/pipelines/libraries/stress/http-windows.yml
index a18de65c264e94..37a09865c764aa 100644
--- a/eng/pipelines/libraries/stress/http-windows.yml
+++ b/eng/pipelines/libraries/stress/http-windows.yml
@@ -13,7 +13,7 @@ steps:
   lfs: false
 
 - powershell: |
-    .\build.cmd -ci -c $(BUILD_CONFIGURATION)
+    .\libraries.cmd -ci -c $(BUILD_CONFIGURATION)
   displayName: Build Corefx
 
 - powershell: |
diff --git a/eng/pipelines/libraries/windows.yml b/eng/pipelines/libraries/windows.yml
index 9ad61b4a64a7f7..229c33ead97cf3 100644
--- a/eng/pipelines/libraries/windows.yml
+++ b/eng/pipelines/libraries/windows.yml
@@ -126,7 +126,7 @@ stages:
 
           frameworkArg: -allConfigurations
           customBuildSteps:
-            - script: build.cmd
+            - script: libraries.cmd
                       -build
                       -configuration $(_BuildConfig)
                       -ci