diff --git a/azure-devops/config.yml b/azure-devops/config.yml
index 6f4bd74b19f..7c96fff32dc 100644
--- a/azure-devops/config.yml
+++ b/azure-devops/config.yml
@@ -7,11 +7,14 @@ variables:
 - name: poolName
   value: 'Stl-2025-10-14T1635-x64-Pool'
   readonly: true
+- name: arm64PoolName
+  value: 'Stl-2025-10-27T1519-arm64-Pool'
+  readonly: true
 - name: poolDemands
   value: 'EnableSpotVM -equals false'
   readonly: true
 - name: vsDevCmdBat
-  value: '%ProgramFiles%\Microsoft Visual Studio\18\Insiders\Common7\Tools\VsDevCmd.bat'
+  value: 'C:\Program Files\Microsoft Visual Studio\18\Insiders\Common7\Tools\VsDevCmd.bat'
   readonly: true
 - name: tmpDir
   value: 'C:\stlTemp'
diff --git a/azure-devops/create-1es-hosted-pool.ps1 b/azure-devops/create-1es-hosted-pool.ps1
index e72d7705f98..53ed679fcc5 100644
--- a/azure-devops/create-1es-hosted-pool.ps1
+++ b/azure-devops/create-1es-hosted-pool.ps1
@@ -7,21 +7,35 @@ Creates a 1ES Hosted Pool, set up for the STL's CI.
 
 .DESCRIPTION
 See https://github.com/microsoft/STL/wiki/Checklist-for-Toolset-Updates for more information.
+
+.PARAMETER Arch
+The architecture can be either x64 or arm64.
 #>
+[CmdletBinding(PositionalBinding=$false)]
+Param(
+  [Parameter(Mandatory)][ValidateSet('x64', 'arm64')][String]$Arch
+)
 
 $ErrorActionPreference = 'Stop'
 
 $CurrentDate = Get-Date
 $Timestamp = $CurrentDate.ToString('yyyy-MM-ddTHHmm')
-$Arch = 'x64'
 
 $Location = 'eastus2'
-$VMSize = 'Standard_F32as_v6'
-$PoolSize = 64
+
+if ($Arch -ieq 'x64') {
+  $VMSize = 'Standard_F32as_v6'
+  $PoolSize = 64
+  $ImagePublisher = 'MicrosoftWindowsServer'
+  $ImageOffer = 'WindowsServer'
+  $ImageSku = '2025-datacenter-azure-edition'
+} else {
+  $VMSize = 'Standard_D32ps_v6'
+  $PoolSize = 32
+  $ImageId = '/SharedGalleries/WindowsServer.1P/Images/2025-datacenter-azure-edition-arm64/Versions/latest'
+}
+
 $ProtoVMName = 'PROTOTYPE'
-$ImagePublisher = 'MicrosoftWindowsServer'
-$ImageOffer = 'WindowsServer'
-$ImageSku = '2025-datacenter-azure-edition'
 
 $LogFile = "1es-hosted-pool-$Timestamp-$Arch.log"
 $ProgressActivity = 'Preparing STL CI pool'
@@ -178,12 +192,21 @@ $Nic = New-AzNetworkInterface `
 ####################################################################################################
 Display-ProgressBar -Status 'Creating prototype VM config'
 
-# Previously: -Priority 'Spot'
-$VM = New-AzVMConfig `
-  -VMName $ProtoVMName `
-  -VMSize $VMSize `
-  -DiskControllerType 'NVMe' `
-  -Priority 'Regular'
+if ($Arch -ieq 'x64') {
+  $VM = New-AzVMConfig `
+    -VMName $ProtoVMName `
+    -VMSize $VMSize `
+    -DiskControllerType 'NVMe' `
+    -Priority 'Regular'
+} else {
+  $VM = New-AzVMConfig `
+    -VMName $ProtoVMName `
+    -VMSize $VMSize `
+    -DiskControllerType 'SCSI' `
+    -Priority 'Regular' `
+    -SecurityType 'TrustedLaunch' `
+    -SharedGalleryImageId $ImageId
+}
 
 ####################################################################################################
 Display-ProgressBar -Status 'Setting prototype VM OS'
@@ -205,12 +228,16 @@ $VM = Add-AzVMNetworkInterface `
 ####################################################################################################
 Display-ProgressBar -Status 'Setting prototype VM source image'
 
-$VM = Set-AzVMSourceImage `
-  -VM $VM `
-  -PublisherName $ImagePublisher `
-  -Offer $ImageOffer `
-  -Skus $ImageSku `
-  -Version 'latest'
+if ($Arch -ieq 'x64') {
+  $VM = Set-AzVMSourceImage `
+    -VM $VM `
+    -PublisherName $ImagePublisher `
+    -Offer $ImageOffer `
+    -Skus $ImageSku `
+    -Version 'latest'
+} else {
+  # We passed -SharedGalleryImageId to New-AzVMConfig above.
+}
 
 ####################################################################################################
 Display-ProgressBar -Status 'Setting prototype VM boot diagnostic'
@@ -242,7 +269,8 @@ Display-ProgressBar -Status 'Running provision-image.ps1 in VM'
 $ProvisionImageResult = Invoke-AzVMRunCommand `
   -ResourceId $VM.ID `
   -CommandId 'RunPowerShellScript' `
-  -ScriptPath "$PSScriptRoot\provision-image.ps1"
+  -ScriptPath "$PSScriptRoot\provision-image.ps1" `
+  -Parameter @{ 'Arch' = $Arch; }
 
 Write-Host $ProvisionImageResult.value.Message
 
@@ -322,7 +350,11 @@ Display-ProgressBar -Status 'Creating image definition'
 
 $ImageDefinitionName = "$ResourceGroupName-ImageDefinition"
 $FeatureTrustedLaunch = @{ Name = 'SecurityType'; Value = 'TrustedLaunch'; }
-$FeatureNVMe = @{ Name = 'DiskControllerTypes'; Value = 'SCSI, NVMe'; }
+if ($Arch -ieq 'x64') {
+  $FeatureNVMe = @{ Name = 'DiskControllerTypes'; Value = 'SCSI, NVMe'; }
+} else {
+  $FeatureNVMe = @{ Name = 'DiskControllerTypes'; Value = 'SCSI'; }
+}
 $ImageDefinitionFeatures = @($FeatureTrustedLaunch, $FeatureNVMe)
 New-AzGalleryImageDefinition `
   -Location $Location `
@@ -331,9 +363,10 @@ New-AzGalleryImageDefinition `
   -Name $ImageDefinitionName `
   -OsState 'Generalized' `
   -OsType 'Windows' `
-  -Publisher $ImagePublisher `
-  -Offer $ImageOffer `
-  -Sku $ImageSku `
+  -Publisher 'StlPublisher' `
+  -Offer 'StlOffer' `
+  -Sku 'StlSku' `
+  -Architecture $Arch `
   -Feature $ImageDefinitionFeatures `
   -HyperVGeneration 'V2' >> $LogFile
 
diff --git a/azure-devops/provision-image.ps1 b/azure-devops/provision-image.ps1
index 62f28d19a93..f4cabac438d 100644
--- a/azure-devops/provision-image.ps1
+++ b/azure-devops/provision-image.ps1
@@ -10,7 +10,14 @@ create-1es-hosted-pool.ps1 (running on an STL maintainer's machine) creates a "p
 then runs provision-image.ps1 on that VM. This gives us full control over what we install for building and testing
 the STL. After provision-image.ps1 is done, create-1es-hosted-pool.ps1 makes an image of the prototype VM,
 creates a 1ES Hosted Pool that will spin up copies of the image as worker VMs, and finally deletes the prototype VM.
+
+.PARAMETER Arch
+The architecture can be either x64 or arm64.
 #>
+[CmdletBinding(PositionalBinding=$false)]
+Param(
+  [Parameter(Mandatory)][ValidateSet('x64', 'arm64')][String]$Arch
+)
 
 $ErrorActionPreference = 'Stop'
 $ProgressPreference = 'SilentlyContinue'
@@ -19,14 +26,12 @@ if ($Env:COMPUTERNAME -cne 'PROTOTYPE') {
   Write-Error 'You should not run provision-image.ps1 on your local machine.'
 }
 
-if ($Env:PROCESSOR_ARCHITECTURE -ceq 'AMD64') {
+if ($Arch -ieq 'x64') {
   Write-Host 'Provisioning x64.'
   $Provisioning_x64 = $true
-} elseif ($Env:PROCESSOR_ARCHITECTURE -ceq 'ARM64') {
+} else {
   Write-Host 'Provisioning ARM64.'
   $Provisioning_x64 = $false
-} else {
-  Write-Error "Unrecognized PROCESSOR_ARCHITECTURE: '$Env:PROCESSOR_ARCHITECTURE'"
 }
 
 $VisualStudioWorkloads = @(
@@ -54,9 +59,9 @@ foreach ($workload in $VisualStudioWorkloads) {
 
 # https://github.com/PowerShell/PowerShell/releases/latest
 if ($Provisioning_x64) {
-  $PowerShellUrl = 'https://github.com/PowerShell/PowerShell/releases/download/v7.5.3/PowerShell-7.5.3-win-x64.msi'
+  $PowerShellUrl = 'https://github.com/PowerShell/PowerShell/releases/download/v7.5.4/PowerShell-7.5.4-win-x64.msi'
 } else {
-  $PowerShellUrl = 'https://github.com/PowerShell/PowerShell/releases/download/v7.5.3/PowerShell-7.5.3-win-arm64.msi'
+  $PowerShellUrl = 'https://github.com/PowerShell/PowerShell/releases/download/v7.5.4/PowerShell-7.5.4-win-arm64.msi'
 }
 $PowerShellArgs = @('/quiet', '/norestart')
 
diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index ca0df15aad7..a01ce02bd8c 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -121,15 +121,15 @@ stages:
     dependsOn: Build_And_Test_x64
     displayName: 'Build and Test ARM64'
     pool:
-      name: ${{ variables.poolName }}
+      name: ${{ variables.arm64PoolName }}
       demands: ${{ variables.poolDemands }}
     jobs:
       - template: azure-devops/build-and-test.yml
         parameters:
-          hostArch: x64
+          hostArch: arm64
           targetArch: arm64
           targetPlatform: arm64
-          testsBuildOnly: true
+          numShards: 10
 
   - stage: Build_And_Test_ARM64EC
     dependsOn: Build_And_Test_x64
diff --git a/tests/libcxx/expected_results.txt b/tests/libcxx/expected_results.txt
index 0253413ab1d..343abccc27a 100644
--- a/tests/libcxx/expected_results.txt
+++ b/tests/libcxx/expected_results.txt
@@ -734,7 +734,9 @@ std/depr/depr.c.headers/tgmath_h.pass.cpp:2 FAIL
 
 # *** CLANG ISSUES, NOT YET ANALYZED ***
 # Not analyzed. Clang apparently defines platform macros differently from C1XX.
-std/language.support/support.limits/limits/numeric.limits.members/traps.pass.cpp:2 FAIL
+# The test inspects `__x86_64__` and `__i386__`, which MSVC doesn't define.
+# SKIPPED because this fails for x64/x86 and passes for ARM64.
+std/language.support/support.limits/limits/numeric.limits.members/traps.pass.cpp:2 SKIPPED
 
 # Not analyzed. Possibly C++20 equality operator rewrite issues.
 std/utilities/expected/expected.expected/equality/equality.other_expected.pass.cpp:2 FAIL