diff --git a/eng/codeOptimization.targets b/eng/codeOptimization.targets
index cbd2474984592a..24e9c761407cfb 100644
--- a/eng/codeOptimization.targets
+++ b/eng/codeOptimization.targets
@@ -9,7 +9,7 @@
            IBCMerge optimizations on Mac for now to unblock the offical build.
            See issue https://github.com/dotnet/runtime/issues/33303
       -->
-      <IsEligibleForNgenOptimization Condition="'$(TargetOS)' == 'OSX'">false</IsEligibleForNgenOptimization>
+      <IsEligibleForNgenOptimization Condition="'$(TargetOS)' == 'OSX' or '$(TargetOS)' == 'iOS'">false</IsEligibleForNgenOptimization>
   </PropertyGroup>
 
   <Target Name="SetApplyNgenOptimization"
diff --git a/eng/install-native-dependencies.sh b/eng/install-native-dependencies.sh
index a73d4918c521bb..e837b017c7cba1 100644
--- a/eng/install-native-dependencies.sh
+++ b/eng/install-native-dependencies.sh
@@ -23,8 +23,18 @@ elif [ "$1" = "OSX" ]; then
     if [ "$?" != "0" ]; then
         exit 1;
     fi
+elif [ "$1" = "iOS" ]; then
+    brew update
+    brew upgrade
+    if [ "$?" != "0" ]; then
+        exit 1;
+    fi
+    brew install openssl autoconf automake libtool pkg-config python3
+    if [ "$?" != "0" ]; then
+        exit 1;
+    fi
 else
-    echo "Must pass \"Linux\" or \"OSX\" as first argument."
+    echo "Must pass \"Linux\", \"iOS\" or \"OSX\" as first argument."
     exit 1
 fi
 
diff --git a/eng/pipelines/common/platform-matrix.yml b/eng/pipelines/common/platform-matrix.yml
index 4858cc154478c6..f67710276d1f25 100644
--- a/eng/pipelines/common/platform-matrix.yml
+++ b/eng/pipelines/common/platform-matrix.yml
@@ -198,6 +198,66 @@ jobs:
 #         asArray: []
 #       ${{ insert }}: ${{ parameters.jobParameters }}
 
+# iOS x64
+
+- ${{ if or(containsValue(parameters.platforms, 'iOS_x64'), eq(parameters.platformGroup, 'all')) }}:
+  - template: xplat-setup.yml
+    parameters:
+      jobTemplate: ${{ parameters.jobTemplate }}
+      helixQueuesTemplate: ${{ parameters.helixQueuesTemplate }}
+      osGroup: iOS
+      archType: x64
+      platform: iOS_x64
+      jobParameters:
+        runtimeFlavor: mono
+        stagedBuild: ${{ parameters.stagedBuild }}
+        buildConfig: ${{ parameters.buildConfig }}
+        ${{ if eq(parameters.passPlatforms, true) }}:
+          platforms: ${{ parameters.platforms }}
+        helixQueueGroup: ${{ parameters.helixQueueGroup }}
+        managedTestBuildOsGroup: OSX
+        ${{ insert }}: ${{ parameters.jobParameters }}
+
+# iOS arm
+
+- ${{ if or(containsValue(parameters.platforms, 'iOS_arm'), eq(parameters.platformGroup, 'all')) }}:
+  - template: xplat-setup.yml
+    parameters:
+      jobTemplate: ${{ parameters.jobTemplate }}
+      helixQueuesTemplate: ${{ parameters.helixQueuesTemplate }}
+      osGroup: iOS
+      archType: arm
+      platform: iOS_x64
+      jobParameters:
+        runtimeFlavor: mono
+        stagedBuild: ${{ parameters.stagedBuild }}
+        buildConfig: ${{ parameters.buildConfig }}
+        ${{ if eq(parameters.passPlatforms, true) }}:
+          platforms: ${{ parameters.platforms }}
+        helixQueueGroup: ${{ parameters.helixQueueGroup }}
+        managedTestBuildOsGroup: OSX
+        ${{ insert }}: ${{ parameters.jobParameters }}
+
+# iOS arm64
+
+- ${{ if or(containsValue(parameters.platforms, 'iOS_arm64'), eq(parameters.platformGroup, 'all')) }}:
+  - template: xplat-setup.yml
+    parameters:
+      jobTemplate: ${{ parameters.jobTemplate }}
+      helixQueuesTemplate: ${{ parameters.helixQueuesTemplate }}
+      osGroup: iOS
+      archType: arm64
+      platform: iOS_x64
+      jobParameters:
+        runtimeFlavor: mono
+        stagedBuild: ${{ parameters.stagedBuild }}
+        buildConfig: ${{ parameters.buildConfig }}
+        ${{ if eq(parameters.passPlatforms, true) }}:
+          platforms: ${{ parameters.platforms }}
+        helixQueueGroup: ${{ parameters.helixQueueGroup }}
+        managedTestBuildOsGroup: OSX
+        ${{ insert }}: ${{ parameters.jobParameters }}
+
 # macOS x64
 
 - ${{ if or(containsValue(parameters.platforms, 'OSX_x64'), eq(parameters.platformGroup, 'all')) }}:
diff --git a/eng/pipelines/common/xplat-setup.yml b/eng/pipelines/common/xplat-setup.yml
index 817443e041e4cf..d644907ae3d63d 100644
--- a/eng/pipelines/common/xplat-setup.yml
+++ b/eng/pipelines/common/xplat-setup.yml
@@ -87,6 +87,10 @@ jobs:
         ${{ if eq(parameters.osGroup, 'OSX') }}:
           vmImage: 'macOS-10.14'
 
+        # Public OSX Build Pool
+        ${{ if eq(parameters.osGroup, 'iOS') }}:
+          vmImage: 'macOS-10.14'
+
         # Official Build Windows Pool
         ${{ if and(eq(parameters.osGroup, 'Windows_NT'), ne(variables['System.TeamProject'], 'public')) }}:
           name: NetCoreInternal-Pool
diff --git a/eng/pipelines/libraries/base-job.yml b/eng/pipelines/libraries/base-job.yml
index 85ea99f75c30f5..e24d0d3328bbc4 100644
--- a/eng/pipelines/libraries/base-job.yml
+++ b/eng/pipelines/libraries/base-job.yml
@@ -40,7 +40,8 @@ jobs:
         - _BuildConfig: ${{ parameters.buildConfig }}
 
         - _msbuildCommonParameters: ''
-        - _stripSymbolsArg: ''
+        # rename this variable, due to collision with build-native.proj
+        - _stripSymbolsArgYaml: ''
         - _runtimeOSArg: ''
         - _finalFrameworkArg: ''
         - _buildScript: $(_buildScriptFileName)$(scriptExt)
@@ -70,6 +71,10 @@ jobs:
         - ${{ if eq(parameters.osGroup, 'WebAssembly') }}:
           - _runtimeOSArg: -os ${{ parameters.osGroup }}
 
+        # force a value for OS when cross-building iOS on OSX
+        - ${{ if eq(parameters.osGroup, 'iOS') }}:
+          - _runtimeOSArg: -os ${{ parameters.osGroup }}
+
         - ${{ if ne(parameters.framework, '') }}:
           - _finalFrameworkArg: -framework ${{ parameters.framework }}
           - _extraHelixArguments: /p:BuildTargetFramework=${{ parameters.framework }}
@@ -107,9 +112,9 @@ jobs:
         - ${{ if ne(parameters.osGroup, 'Windows_NT') }}:
           - _buildScript: ./$(_buildScriptFileName)$(scriptExt)
           - ${{ if eq(parameters.isOfficialBuild, 'true') }}:
-            - _stripSymbolsArg: -stripSymbols
+            - _stripSymbolsArgYaml: -stripSymbols
 
-        - _buildArguments: -configuration ${{ parameters.buildConfig }} -ci -arch ${{ parameters.archType }} $(_finalFrameworkArg) $(_stripSymbolsArg) $(_testScopeArg) $(_warnAsErrorArg) $(_runtimeOSArg) $(_msbuildCommonParameters) $(_runtimeArtifactsPathArg) $(_crossBuildPropertyArg)
+        - _buildArguments: -configuration ${{ parameters.buildConfig }} -ci -arch ${{ parameters.archType }} $(_finalFrameworkArg) $(_stripSymbolsArgYaml) $(_testScopeArg) $(_warnAsErrorArg) $(_runtimeOSArg) $(_msbuildCommonParameters) $(_runtimeArtifactsPathArg) $(_crossBuildPropertyArg)
         - ${{ parameters.variables }}
 
       dependsOn:
diff --git a/eng/pipelines/mono/templates/build-job.yml b/eng/pipelines/mono/templates/build-job.yml
index d23bfded5a4e8f..e554e749a1c83c 100644
--- a/eng/pipelines/mono/templates/build-job.yml
+++ b/eng/pipelines/mono/templates/build-job.yml
@@ -67,6 +67,9 @@ jobs:
         value: /p:OutputRid=linux-musl-${{ parameters.archType }}
       - name: _PortableBuild
         value: true
+    - ${{ if eq(parameters.osGroup, 'iOS') }}:
+      - name: osOverride
+        value: -os iOS
     - ${{ parameters.variables }}
 
     steps:
@@ -75,7 +78,7 @@ jobs:
     # Linux builds use docker images with dependencies preinstalled,
     # and FreeBSD builds use a build agent with dependencies
     # preinstalled, so we only need this step for OSX and Windows.
-    - ${{ if eq(parameters.osGroup, 'OSX') }}:
+    - ${{ if in(parameters.osGroup, 'OSX', 'iOS') }}:
       - script: sh $(Build.SourcesDirectory)/eng/install-native-dependencies.sh $(osGroup)
         displayName: Install native dependencies
     - ${{ if eq(parameters.osGroup, 'Windows_NT') }}:
@@ -85,10 +88,10 @@ jobs:
 
     # Build
     - ${{ if ne(parameters.osGroup, 'Windows_NT') }}:
-      - script: ./mono$(scriptExt) -configuration $(buildConfig) -arch $(archType) -ci /p:MonoEnableLLVM=${{ parameters.llvm }}
+      - script: ./mono$(scriptExt) -configuration $(buildConfig) -arch $(archType) $(osOverride) -ci /p:MonoEnableLLVM=${{ parameters.llvm }}
         displayName: Build product
     - ${{ if eq(parameters.osGroup, 'Windows_NT') }}:
-      - script: mono$(scriptExt) -configuration $(buildConfig) -arch $(archType) -ci /p:MonoEnableLLVM=${{ parameters.llvm }}
+      - script: mono$(scriptExt) -configuration $(buildConfig) -arch $(archType) $(osOverride) -ci /p:MonoEnableLLVM=${{ parameters.llvm }}
         displayName: Build product
 
     # Publish product output directory for consumption by tests.
@@ -104,10 +107,10 @@ jobs:
 
     # Build packages
     - ${{ if and(ne(parameters.llvm, true), ne(parameters.osGroup, 'Windows_NT')) }}:
-      - script: ./mono$(scriptExt) -configuration $(buildConfig) -arch $(archType) -ci $(officialBuildIdArg) /p:MonoEnableLLVM=${{ parameters.llvm }} -pack $(OutputRidArg)
+      - script: ./mono$(scriptExt) -configuration $(buildConfig) -arch $(archType) $(osOverride) -ci $(officialBuildIdArg) /p:MonoEnableLLVM=${{ parameters.llvm }} -pack $(OutputRidArg)
         displayName: Build nupkg
     - ${{ if and(ne(parameters.llvm, true), eq(parameters.osGroup, 'Windows_NT')) }}:
-      - script: mono$(scriptExt) -configuration $(buildConfig) -arch $(archType) -ci $(officialBuildIdArg) /p:MonoEnableLLVM=${{ parameters.llvm }} -pack $(OutputRidArg)
+      - script: mono$(scriptExt) -configuration $(buildConfig) -arch $(archType) $(osOverride) -ci $(officialBuildIdArg) /p:MonoEnableLLVM=${{ parameters.llvm }} -pack $(OutputRidArg)
         displayName: Build nupkg
 
     # Save packages using the prepare-signed-artifacts format.
diff --git a/eng/pipelines/mono/templates/xplat-job.yml b/eng/pipelines/mono/templates/xplat-job.yml
index 8d7465d7f88453..2cd61dc7e7f3e4 100644
--- a/eng/pipelines/mono/templates/xplat-job.yml
+++ b/eng/pipelines/mono/templates/xplat-job.yml
@@ -56,7 +56,7 @@ jobs:
       agentOs: Ubuntu
     ${{ if eq(parameters.osGroup, 'FreeBSD') }}:
       agentOs: FreeBSD
-    ${{ if eq(parameters.osGroup, 'OSX') }}:
+    ${{ if in(parameters.osGroup, 'OSX', 'iOS') }}:
       agentOs: MacOS
     ${{ if eq(parameters.osGroup, 'Windows_NT') }}:
       agentOs: Windows_NT
diff --git a/eng/pipelines/runtime-official.yml b/eng/pipelines/runtime-official.yml
index 7619c2e533e1b8..a49a4b1bbda73e 100644
--- a/eng/pipelines/runtime-official.yml
+++ b/eng/pipelines/runtime-official.yml
@@ -69,6 +69,9 @@ stages:
       runtimeFlavor: mono
       buildConfig: release
       platforms:
+      - iOS_x64
+      - iOS_arm
+      - iOS_arm64
       - OSX_x64
       - Linux_x64
       - Linux_arm
@@ -104,6 +107,22 @@ stages:
         isOfficialBuild: ${{ variables.isOfficialBuild }}
         liveRuntimeBuildConfig: release
 
+  #
+  # Build libraries using live CoreLib from Mono
+  #
+  - template: /eng/pipelines/common/platform-matrix.yml
+    parameters:
+      jobTemplate: /eng/pipelines/libraries/build-job.yml
+      buildConfig: Release
+      runtimeFlavor: mono
+      platforms:
+      - iOS_x64
+      - iOS_arm
+      - iOS_arm64
+      jobParameters:
+        isOfficialBuild: ${{ variables.isOfficialBuild }}
+        liveRuntimeBuildConfig: release
+
   #
   # Build libraries AllConfigurations for packages
   #
diff --git a/eng/pipelines/runtime.yml b/eng/pipelines/runtime.yml
index 4965c687d5ba2a..b7de8cfaf894c9 100644
--- a/eng/pipelines/runtime.yml
+++ b/eng/pipelines/runtime.yml
@@ -226,6 +226,9 @@ jobs:
     runtimeFlavor: mono
     buildConfig: debug
     platforms:
+    - iOS_x64
+    - iOS_arm
+    - iOS_arm64
     - OSX_x64
     - Linux_x64
     - Linux_arm
@@ -253,6 +256,9 @@ jobs:
     runtimeFlavor: mono
     buildConfig: release
     platforms:
+    - iOS_x64
+    - iOS_arm
+    - iOS_arm64
     - OSX_x64
     - Linux_x64
     - Linux_arm
@@ -357,6 +363,34 @@ jobs:
     - Windows_NT_x64
     jobParameters:
       liveRuntimeBuildConfig: release
+
+#
+# Build libraries using Mono CoreLib only
+#
+- template: /eng/pipelines/common/platform-matrix.yml
+  parameters:
+    jobTemplate: /eng/pipelines/libraries/build-job.yml
+    buildConfig: Release
+    runtimeFlavor: mono
+    platforms:
+    - iOS_arm
+    - iOS_arm64
+    - iOS_x64
+    jobParameters:
+      liveRuntimeBuildConfig: release
+
+- template: /eng/pipelines/common/platform-matrix.yml
+  parameters:
+    jobTemplate: /eng/pipelines/libraries/build-job.yml
+    buildConfig: Debug
+    runtimeFlavor: mono
+    platforms:
+    - iOS_arm
+    - iOS_arm64
+    - iOS_x64
+    jobParameters:
+      liveRuntimeBuildConfig: debug
+
 #
 # Libraries Build that only run when libraries is changed
 #