diff --git a/.github/workflows/build-and-test.yml b/.github/workflows/build-and-test.yml
index af6e47f6..32567749 100644
--- a/.github/workflows/build-and-test.yml
+++ b/.github/workflows/build-and-test.yml
@@ -41,6 +41,11 @@ jobs:
       shell: pwsh
       run: swift build --verbose --build-tests
 
+    - name: Build mscorlib.winmd
+      working-directory: Generator
+      shell: pwsh
+      run: .\SPMPostBuild.ps1 -Config debug
+
     - name: Test code generator
       working-directory: Generator
       shell: pwsh
@@ -49,8 +54,7 @@ jobs:
     - name: Build WinRTComponent
       working-directory: InteropTests
       shell: pwsh
-      run: |
-        & .\SPMPrebuild.ps1 -SwiftWinRT "$Env:GITHUB_WORKSPACE\Generator\.build\debug\SwiftWinRT.exe"
+      run: .\SPMPrebuild.ps1 -SwiftWinRT "$Env:GITHUB_WORKSPACE\Generator\.build\debug\SwiftWinRT.exe"
 
     - name: Build InteropTests
       working-directory: InteropTests
diff --git a/Generator/Dependencies/swift-dotnetmetadata/CMakeLists.txt b/Generator/Dependencies/swift-dotnetmetadata/CMakeLists.txt
index 1d0e7fb8..236affed 100644
--- a/Generator/Dependencies/swift-dotnetmetadata/CMakeLists.txt
+++ b/Generator/Dependencies/swift-dotnetmetadata/CMakeLists.txt
@@ -1,7 +1,7 @@
 FetchContent_Declare(
     swift-dotnetmetadata
     GIT_REPOSITORY https://github.com/tristanlabelle/swift-dotnetmetadata.git
-    GIT_TAG 20790178c573dcc2238fa2af8680c0e6f23f7c5e
+    GIT_TAG b4870688be31d889ed51da9beac466ede9f366dd
     SOURCE_SUBDIR "don't use cmakelists")
 FetchContent_MakeAvailable(swift-dotnetmetadata)
 
diff --git a/Generator/Package.resolved b/Generator/Package.resolved
index 847c6354..95852fb3 100644
--- a/Generator/Package.resolved
+++ b/Generator/Package.resolved
@@ -24,7 +24,7 @@
       "location" : "https://github.com/tristanlabelle/swift-dotnetmetadata",
       "state" : {
         "branch" : "main",
-        "revision" : "20790178c573dcc2238fa2af8680c0e6f23f7c5e"
+        "revision" : "b4870688be31d889ed51da9beac466ede9f366dd"
       }
     }
   ],
diff --git a/Generator/SPMPostBuild.ps1 b/Generator/SPMPostBuild.ps1
new file mode 100644
index 00000000..ee2f68fe
--- /dev/null
+++ b/Generator/SPMPostBuild.ps1
@@ -0,0 +1,26 @@
+<#
+.SYNOPSIS
+Builds mscorlib.winmd and locates it next to SwiftWinRT.exe.
+
+.PARAMETER Config
+The build configuration that was used to build SwiftWinRT.exe.
+#>
+[CmdletBinding(PositionalBinding = $false)]
+param(
+    [Parameter(Mandatory = $true)]
+    [string] $Config
+)
+
+$TargetTripleArch = switch ($Env:PROCESSOR_ARCHITECTURE) {
+    "amd64" { "x86_64" }
+    "arm64" { "aarch64" }
+    "x86" { "i686" }
+    default { throw "Unsupported architecture: $Env:PROCESSOR_ARCHITECTURE" }
+}
+
+$BinaryDir = "$PSScriptRoot\.build\$TargetTripleArch-unknown-windows-msvc\$Config"
+if (-not (Test-Path $BinaryDir)) {
+    throw "The binary directory does not exist: $BinaryDir"
+}
+
+& "$PSScriptRoot\.build\checkouts\swift-dotnetmetadata\WindowsMetadataCoreLibrary\Assemble.ps1" -OutputPath "$BinaryDir\mscorlib.winmd"
\ No newline at end of file
diff --git a/Generator/Sources/SwiftWinRT/CommandLineArguments.swift b/Generator/Sources/SwiftWinRT/CommandLineArguments.swift
index ba69def2..80214034 100644
--- a/Generator/Sources/SwiftWinRT/CommandLineArguments.swift
+++ b/Generator/Sources/SwiftWinRT/CommandLineArguments.swift
@@ -7,6 +7,9 @@ struct CommandLineArguments: ParsableCommand {
             abstract: "A WinRT projections generator for Swift.")
     }
 
+    @Option(name: .customLong("mscorlib"), help: .init("A path to the mscorlib.winmd/dll to use. Defaults to looking for mscorlib.winmd next to the exe.", valueName: "path"))
+    var mscorlibPath: String? = nil
+
     @Option(name: .customLong("reference"), help: .init("A path to a .winmd file with the APIs to project.", valueName: "file"))
     var references: [String] = []
 
diff --git a/Generator/Sources/SwiftWinRT/main.swift b/Generator/Sources/SwiftWinRT/main.swift
index 62a63c8b..c920be87 100644
--- a/Generator/Sources/SwiftWinRT/main.swift
+++ b/Generator/Sources/SwiftWinRT/main.swift
@@ -22,12 +22,8 @@ do {
     let spmOptions = SPMOptions(commandLineArguments: commandLineArguments, projectionConfig: projectionConfig)
     let cmakeOptions = CMakeOptions(commandLineArguments: commandLineArguments, projectionConfig: projectionConfig)
 
-    // Resolve the mscorlib dependency from the .NET Framework 4 machine installation
     let context = WinMDLoadContext()
-    guard let mscorlibPath = SystemAssemblies.DotNetFramework4.mscorlibPath else {
-        throw AssemblyLoadError.notFound(message: "mscorlib was not found on the machine.")
-    }
-    _ = try context.load(path: mscorlibPath)
+    _ = try context.load(path: commandLineArguments.mscorlibPath ?? getDefaultMscorlibPath())
 
     let projection = try createProjection(
         commandLineArguments: commandLineArguments,
@@ -52,4 +48,12 @@ catch let error {
     print(error)
     fflush(stdout)
     throw error
+}
+
+func getDefaultMscorlibPath() -> String {
+    Bundle.main.executableURL!
+        .deletingLastPathComponent()
+        .appendingPathComponent("mscorlib.winmd", isDirectory: false)
+        .path
+        .replacingOccurrences(of: "/", with: "\\")
 }
\ No newline at end of file
diff --git a/InteropTests/SPMPrebuild.ps1 b/InteropTests/SPMPrebuild.ps1
index ce42dd22..e20fdecf 100644
--- a/InteropTests/SPMPrebuild.ps1
+++ b/InteropTests/SPMPrebuild.ps1
@@ -18,23 +18,26 @@ $ErrorActionPreference = "Stop"
 
 if (-not $SwiftWinRT) {
     Write-Host -ForegroundColor Cyan "Building SwiftWinRT.exe with SPM..."
-    $SwiftConfiguration = "debug"
+    $BuildConfig = "debug"
     $RepoRoot = (& git.exe -C "$PSScriptRoot" rev-parse --path-format=absolute --show-toplevel).Trim()
     $GeneratorProjectDir = "$RepoRoot\Generator"
 
     & swift.exe build `
         --package-path $GeneratorProjectDir `
-        --configuration $SwiftConfiguration `
+        --configuration $BuildConfig `
         --build-path "$GeneratorProjectDir\.build"
     if ($LASTEXITCODE -ne 0) { throw "Failed to build SwiftWinRT.exe" }
 
+    & "$GeneratorProjectDir\SPMPostBuild.ps1" -Config $BuildConfig
+
     $TargetTripleArch = switch ($Env:PROCESSOR_ARCHITECTURE) {
         "amd64" { "x86_64" }
         "arm64" { "aarch64" }
         "x86" { "i686" }
         default { throw "Unsupported architecture: $Env:PROCESSOR_ARCHITECTURE" }
     }
-    $SwiftWinRT = "$GeneratorProjectDir\.build\$TargetTripleArch-unknown-windows-msvc\$SwiftConfiguration\SwiftWinRT.exe"
+
+    $SwiftWinRT = "$GeneratorProjectDir\.build\$TargetTripleArch-unknown-windows-msvc\$BuildConfig\SwiftWinRT.exe"
 }
 else {
     $SwiftWinRT = [IO.Path]::GetFullPath($SwiftWinRT)