diff --git a/Sources/BuildSystemIntegration/CompilationDatabase.swift b/Sources/BuildSystemIntegration/CompilationDatabase.swift
index 817b893b..91037ce7 100644
--- a/Sources/BuildSystemIntegration/CompilationDatabase.swift
+++ b/Sources/BuildSystemIntegration/CompilationDatabase.swift
@@ -34,6 +34,10 @@ import struct TSCBasic.RelativePath
 import var TSCBasic.localFileSystem
 #endif
 
+#if os(Windows)
+import WinSDK
+#endif
+
 /// A single compilation database command.
 ///
 /// See https://clang.llvm.org/docs/JSONCompilationDatabase.html
@@ -97,7 +101,7 @@ package struct CompilationDatabaseCompileCommand: Equatable, Codable {
   /// it falls back to `filename`, which is more likely to be the identifier
   /// that a caller will be looking for.
   package var uri: DocumentURI {
-    if filename.hasPrefix("/") || !directory.hasPrefix("/") {
+    if filename.isAbsolutePath || !directory.isAbsolutePath {
       return DocumentURI(filePath: filename, isDirectory: false)
     } else {
       return DocumentURI(URL(fileURLWithPath: directory).appendingPathComponent(filename, isDirectory: false))
@@ -288,3 +292,15 @@ enum CompilationDatabaseDecodingError: Error {
   case missingCommandOrArguments
   case fixedDatabaseDecodingError
 }
+
+fileprivate extension String {
+  var isAbsolutePath: Bool {
+    #if os(Windows)
+    Array(self.utf16).withUnsafeBufferPointer { buffer in
+      return !PathIsRelativeW(buffer.baseAddress)
+    }
+    #else
+    return self.hasPrefix("/")
+    #endif
+  }
+}
diff --git a/Sources/SKSupport/DocumentURI+symlinkTarget.swift b/Sources/SKSupport/DocumentURI+symlinkTarget.swift
index 083c4e63..34a15df6 100644
--- a/Sources/SKSupport/DocumentURI+symlinkTarget.swift
+++ b/Sources/SKSupport/DocumentURI+symlinkTarget.swift
@@ -27,10 +27,10 @@ extension DocumentURI {
     guard let fileUrl = fileURL else {
       return nil
     }
-    let realpath = fileUrl.realpath
-    if realpath == fileURL {
+    let realpath = DocumentURI(fileUrl.realpath)
+    if realpath == self {
       return nil
     }
-    return DocumentURI(realpath)
+    return realpath
   }
 }
diff --git a/Sources/SKTestSupport/BuildServerTestProject.swift b/Sources/SKTestSupport/BuildServerTestProject.swift
index 43c1ae4f..fc50c149 100644
--- a/Sources/SKTestSupport/BuildServerTestProject.swift
+++ b/Sources/SKTestSupport/BuildServerTestProject.swift
@@ -17,7 +17,7 @@ import XCTest
 fileprivate let sdkArgs =
   if let defaultSDKPath {
     """
-    "-sdk", "\(defaultSDKPath)",
+    "-sdk", "\(defaultSDKPath.replacing(#"\"#, with: #"\\"#))",
     """
   } else {
     ""
diff --git a/Sources/SKTestSupport/FindTool.swift b/Sources/SKTestSupport/FindTool.swift
index 0f6207e4..d134e715 100644
--- a/Sources/SKTestSupport/FindTool.swift
+++ b/Sources/SKTestSupport/FindTool.swift
@@ -48,8 +48,14 @@ package func findTool(name: String) async -> URL? {
     return nil
   }
   #if os(Windows)
-  path = String((path.split { $0.isNewline })[0])
+  // where.exe returns all files that match the name. We only care about the first one.
+  if let newlineIndex = path.firstIndex(where: \.isNewline) {
+    path = String(path[..<newlineIndex])
+  }
   #endif
   path = path.trimmingCharacters(in: .whitespacesAndNewlines)
+  if path.isEmpty {
+    return nil
+  }
   return URL(fileURLWithPath: path, isDirectory: false)
 }
diff --git a/Sources/SKTestSupport/IndexedSingleSwiftFileTestProject.swift b/Sources/SKTestSupport/IndexedSingleSwiftFileTestProject.swift
index 90c25b1b..2f1291b0 100644
--- a/Sources/SKTestSupport/IndexedSingleSwiftFileTestProject.swift
+++ b/Sources/SKTestSupport/IndexedSingleSwiftFileTestProject.swift
@@ -87,6 +87,19 @@ package struct IndexedSingleSwiftFileTestProject {
 
       // The following are needed so we can import XCTest
       let sdkUrl = URL(fileURLWithPath: sdk)
+      #if os(Windows)
+      let xctestModuleDir =
+        sdkUrl
+        .deletingLastPathComponent()
+        .deletingLastPathComponent()
+        .appendingPathComponent("Library")
+        .appendingPathComponent("XCTest-development")
+        .appendingPathComponent("usr")
+        .appendingPathComponent("lib")
+        .appendingPathComponent("swift")
+        .appendingPathComponent("windows")
+      compilerArguments += ["-I", xctestModuleDir.path]
+      #else
       let usrLibDir =
         sdkUrl
         .deletingLastPathComponent()
@@ -103,6 +116,7 @@ package struct IndexedSingleSwiftFileTestProject {
         "-I", usrLibDir.path,
         "-F", frameworksDir.path,
       ]
+      #endif
     }
 
     let compilationDatabase = JSONCompilationDatabase(
diff --git a/Sources/SKTestSupport/MultiFileTestProject.swift b/Sources/SKTestSupport/MultiFileTestProject.swift
index da509c79..93bcadca 100644
--- a/Sources/SKTestSupport/MultiFileTestProject.swift
+++ b/Sources/SKTestSupport/MultiFileTestProject.swift
@@ -102,7 +102,10 @@ package class MultiFileTestProject {
 
     var fileData: [String: FileData] = [:]
     for (fileLocation, markedText) in files {
-      let markedText = markedText.replacingOccurrences(of: "$TEST_DIR", with: scratchDirectory.path)
+      let markedText =
+        markedText
+        .replacingOccurrences(of: "$TEST_DIR_URL", with: scratchDirectory.absoluteString)
+        .replacingOccurrences(of: "$TEST_DIR", with: scratchDirectory.path)
       let fileURL = fileLocation.url(relativeTo: scratchDirectory)
       try FileManager.default.createDirectory(
         at: fileURL.deletingLastPathComponent(),
diff --git a/Sources/SKTestSupport/Utils.swift b/Sources/SKTestSupport/Utils.swift
index fafb764f..f223d28b 100644
--- a/Sources/SKTestSupport/Utils.swift
+++ b/Sources/SKTestSupport/Utils.swift
@@ -68,10 +68,17 @@ package func testScratchDir(testName: String = #function) throws -> URL {
   if let firstDash = uuid.firstIndex(of: "-") {
     uuid = uuid[..<firstDash]
   }
-  let url = FileManager.default.temporaryDirectory
-    .realpath
+  // Including the test name in the directory frequently makes path lengths of test files exceed the maximum path length
+  // on Windows. Choose shorter directory names on that platform to avoid that issue.
+  #if os(Windows)
+  let url = FileManager.default.temporaryDirectory.realpath
+    .appendingPathComponent("lsp-test")
+    .appendingPathComponent("\(uuid)")
+  #else
+  let url = FileManager.default.temporaryDirectory.realpath
     .appendingPathComponent("sourcekit-lsp-test-scratch")
     .appendingPathComponent("\(testBaseName)-\(uuid)")
+  #endif
   try? FileManager.default.removeItem(at: url)
   try FileManager.default.createDirectory(at: url, withIntermediateDirectories: true)
   return url
diff --git a/Sources/SourceKitLSP/Clang/ClangLanguageService.swift b/Sources/SourceKitLSP/Clang/ClangLanguageService.swift
index b6ec03aa..8c0cb94a 100644
--- a/Sources/SourceKitLSP/Clang/ClangLanguageService.swift
+++ b/Sources/SourceKitLSP/Clang/ClangLanguageService.swift
@@ -326,7 +326,7 @@ actor ClangLanguageService: LanguageService, MessageHandler {
       // safer, can also indefinitely hang as `CreateRemoteThread` may not be serviced depending on the state of
       // the process. This just attempts to terminate the process, risking a deadlock and resource leaks, which is fine
       // since we only use `crash` from tests.
-      _ = TerminateProcess(self.hClangd, 0)
+      _ = TerminateProcess(self.hClangd, 255)
     }
     #else
     if let pid = self.clangdPid {
diff --git a/Tests/BuildSystemIntegrationTests/BuildServerBuildSystemTests.swift b/Tests/BuildSystemIntegrationTests/BuildServerBuildSystemTests.swift
index 9f8426be..a59a1fc0 100644
--- a/Tests/BuildSystemIntegrationTests/BuildServerBuildSystemTests.swift
+++ b/Tests/BuildSystemIntegrationTests/BuildServerBuildSystemTests.swift
@@ -53,7 +53,7 @@ final class BuildServerBuildSystemTests: XCTestCase {
                 {
                   "target": {"uri": "bsp://dummy"},
                   "sources": [
-                    {"uri": "file://$TEST_DIR/Test.swift", "kind": 1, "generated": False}
+                    {"uri": "$TEST_DIR_URL/Test.swift", "kind": 1, "generated": False}
                   ],
                 }
               ]
@@ -123,7 +123,7 @@ final class BuildServerBuildSystemTests: XCTestCase {
                 {
                   "target": {"uri": "bsp://dummy"},
                   "sources": [
-                    {"uri": "file://$TEST_DIR/Test.swift", "kind": 1, "generated": False}
+                    {"uri": "$TEST_DIR_URL/Test.swift", "kind": 1, "generated": False}
                   ],
                 }
               ]
@@ -197,7 +197,7 @@ final class BuildServerBuildSystemTests: XCTestCase {
                 {
                   "target": {"uri": "bsp://dummy"},
                   "sources": [
-                    {"uri": "file://$TEST_DIR/Test.swift", "kind": 1, "generated": False}
+                    {"uri": "$TEST_DIR_URL/Test.swift", "kind": 1, "generated": False}
                   ],
                 }
               ]
@@ -273,8 +273,8 @@ final class BuildServerBuildSystemTests: XCTestCase {
                 {
                   "target": {"uri": "bsp://dummy"},
                   "sources": [
-                    {"uri": "file://$TEST_DIR/Crash.swift", "kind": 1, "generated": False},
-                    {"uri": "file://$TEST_DIR/Test.swift", "kind": 1, "generated": False},
+                    {"uri": "$TEST_DIR_URL/Crash.swift", "kind": 1, "generated": False},
+                    {"uri": "$TEST_DIR_URL/Test.swift", "kind": 1, "generated": False},
                   ],
                 }
               ]
diff --git a/Tests/BuildSystemIntegrationTests/CompilationDatabaseTests.swift b/Tests/BuildSystemIntegrationTests/CompilationDatabaseTests.swift
index 32874f8c..c727be4b 100644
--- a/Tests/BuildSystemIntegrationTests/CompilationDatabaseTests.swift
+++ b/Tests/BuildSystemIntegrationTests/CompilationDatabaseTests.swift
@@ -152,16 +152,27 @@ final class CompilationDatabaseTests: XCTestCase {
     )
   }
 
-  func testJSONCompilationDatabaseLookup() {
+  func testJSONCompilationDatabaseLookup() throws {
+    #if os(Windows)
+    let fileSystemRoot = "c:/"
+    #else
+    let fileSystemRoot = "/"
+    #endif
+
     let cmd1 = CompilationDatabase.Command(directory: "a", filename: "b", commandLine: [], output: nil)
-    let cmd2 = CompilationDatabase.Command(directory: "/c", filename: "b", commandLine: [], output: nil)
-    let cmd3 = CompilationDatabase.Command(directory: "/c", filename: "/b", commandLine: [], output: nil)
+    let cmd2 = CompilationDatabase.Command(directory: "\(fileSystemRoot)c", filename: "b", commandLine: [], output: nil)
+    let cmd3 = CompilationDatabase.Command(
+      directory: "\(fileSystemRoot)c",
+      filename: "\(fileSystemRoot)b",
+      commandLine: [],
+      output: nil
+    )
 
     let db = JSONCompilationDatabase([cmd1, cmd2, cmd3])
 
     XCTAssertEqual(db[DocumentURI(filePath: "b", isDirectory: false)], [cmd1])
-    XCTAssertEqual(db[DocumentURI(filePath: "/c/b", isDirectory: false)], [cmd2])
-    XCTAssertEqual(db[DocumentURI(filePath: "/b", isDirectory: false)], [cmd3])
+    XCTAssertEqual(db[DocumentURI(filePath: "\(fileSystemRoot)c/b", isDirectory: false)], [cmd2])
+    XCTAssertEqual(db[DocumentURI(filePath: "\(fileSystemRoot)b", isDirectory: false)], [cmd3])
   }
 
   func testJSONCompilationDatabaseFromDirectory() throws {
@@ -250,19 +261,16 @@ final class CompilationDatabaseTests: XCTestCase {
         """
     )
 
-    let db = try tryLoadCompilationDatabase(
-      directory: AbsolutePath(validating: "/a"),
-      fs
-    )
-    XCTAssertNotNil(db)
+    let db = try XCTUnwrap(tryLoadCompilationDatabase(directory: AbsolutePath(validating: "/a"), fs))
 
+    // Note: Use `AbsolutePath(validating:).pathString` to normalize forward slashes to backslashes on Windows
     XCTAssertEqual(
-      db![DocumentURI(filePath: "/a/b", isDirectory: false)],
+      db[DocumentURI(filePath: "/a/b", isDirectory: false)],
       [
         CompilationDatabase.Command(
           directory: try AbsolutePath(validating: "/a").pathString,
-          filename: "/a/b",
-          commandLine: ["clang", "-xc++", "-I", "libwidget/include/", "/a/b"],
+          filename: try AbsolutePath(validating: "/a/b").pathString,
+          commandLine: ["clang", "-xc++", "-I", "libwidget/include/", try AbsolutePath(validating: "/a/b").pathString],
           output: nil
         )
       ]
diff --git a/Tests/BuildSystemIntegrationTests/FallbackBuildSettingsTests.swift b/Tests/BuildSystemIntegrationTests/FallbackBuildSettingsTests.swift
index fb03bf09..0698a8cf 100644
--- a/Tests/BuildSystemIntegrationTests/FallbackBuildSettingsTests.swift
+++ b/Tests/BuildSystemIntegrationTests/FallbackBuildSettingsTests.swift
@@ -22,7 +22,7 @@ import struct PackageModel.BuildFlags
 final class FallbackBuildSystemTests: XCTestCase {
 
   func testSwift() throws {
-    let sdk = "/my/sdk"
+    let sdk = try AbsolutePath(validating: "/my/sdk").pathString
     let source = DocumentURI(filePath: "/my/source.swift", isDirectory: false)
 
     XCTAssertEqual(
@@ -32,7 +32,7 @@ final class FallbackBuildSystemTests: XCTestCase {
   }
 
   func testSwiftWithCustomFlags() throws {
-    let sdk = "/my/sdk"
+    let sdk = try AbsolutePath(validating: "/my/sdk").pathString
     let source = DocumentURI(filePath: "/my/source.swift", isDirectory: false)
 
     let options = SourceKitLSPOptions.FallbackBuildSystemOptions(
@@ -49,7 +49,7 @@ final class FallbackBuildSystemTests: XCTestCase {
   }
 
   func testSwiftWithCustomSDKFlag() throws {
-    let sdk = "/my/sdk"
+    let sdk = try AbsolutePath(validating: "/my/sdk").pathString
     let source = DocumentURI(filePath: "/my/source.swift", isDirectory: false)
 
     let options = SourceKitLSPOptions.FallbackBuildSystemOptions(
@@ -63,7 +63,7 @@ final class FallbackBuildSystemTests: XCTestCase {
   }
 
   func testCXX() throws {
-    let sdk = "/my/sdk"
+    let sdk = try AbsolutePath(validating: "/my/sdk").pathString
     let source = DocumentURI(filePath: "/my/source.cpp", isDirectory: false)
 
     XCTAssertEqual(
@@ -77,7 +77,7 @@ final class FallbackBuildSystemTests: XCTestCase {
   }
 
   func testCXXWithCustomFlags() throws {
-    let sdk = "/my/sdk"
+    let sdk = try AbsolutePath(validating: "/my/sdk").pathString
     let source = DocumentURI(filePath: "/my/source.cpp", isDirectory: false)
 
     let options = SourceKitLSPOptions.FallbackBuildSystemOptions(
@@ -92,7 +92,7 @@ final class FallbackBuildSystemTests: XCTestCase {
   }
 
   func testCXXWithCustomIsysroot() throws {
-    let sdk = "/my/sdk"
+    let sdk = try AbsolutePath(validating: "/my/sdk").pathString
     let source = DocumentURI(filePath: "/my/source.cpp", isDirectory: false)
 
     let options = SourceKitLSPOptions.FallbackBuildSystemOptions(
@@ -111,7 +111,7 @@ final class FallbackBuildSystemTests: XCTestCase {
   }
 
   func testC() throws {
-    let sdk = "/my/sdk"
+    let sdk = try AbsolutePath(validating: "/my/sdk").pathString
     let source = DocumentURI(filePath: "/my/source.c", isDirectory: false)
 
     XCTAssertEqual(
@@ -121,7 +121,7 @@ final class FallbackBuildSystemTests: XCTestCase {
   }
 
   func testCWithCustomFlags() throws {
-    let sdk = "/my/sdk"
+    let sdk = try AbsolutePath(validating: "/my/sdk").pathString
     let source = DocumentURI(filePath: "/my/source.c", isDirectory: false)
 
     let options = SourceKitLSPOptions.FallbackBuildSystemOptions(
@@ -136,7 +136,7 @@ final class FallbackBuildSystemTests: XCTestCase {
   }
 
   func testObjC() throws {
-    let sdk = "/my/sdk"
+    let sdk = try AbsolutePath(validating: "/my/sdk").pathString
     let source = DocumentURI(filePath: "/my/source.m", isDirectory: false)
 
     XCTAssertEqual(
@@ -146,7 +146,7 @@ final class FallbackBuildSystemTests: XCTestCase {
   }
 
   func testObjCXX() throws {
-    let sdk = "/my/sdk"
+    let sdk = try AbsolutePath(validating: "/my/sdk").pathString
     let source = DocumentURI(filePath: "/my/source.mm", isDirectory: false)
 
     XCTAssertEqual(
diff --git a/Tests/BuildSystemIntegrationTests/SwiftPMBuildSystemTests.swift b/Tests/BuildSystemIntegrationTests/SwiftPMBuildSystemTests.swift
index 26f88256..e14319a4 100644
--- a/Tests/BuildSystemIntegrationTests/SwiftPMBuildSystemTests.swift
+++ b/Tests/BuildSystemIntegrationTests/SwiftPMBuildSystemTests.swift
@@ -169,7 +169,7 @@ final class SwiftPMBuildSystemTests: XCTestCase {
           """,
         ]
       )
-      let packageRoot = try resolveSymlinks(tempDir.appending(component: "pkg"))
+      let packageRoot = try AbsolutePath(validating: tempDir.appending(component: "pkg").asURL.realpath.path)
       let buildSystemManager = await BuildSystemManager(
         buildSystemKind: .swiftPM(projectRoot: packageRoot),
         toolchainRegistry: .forTesting,
@@ -182,9 +182,15 @@ final class SwiftPMBuildSystemTests: XCTestCase {
       let aPlusSomething = packageRoot.appending(components: "Sources", "lib", "a+something.swift")
 
       assertNotNil(await buildSystemManager.initializationData?.indexStorePath)
+      let pathWithPlusEscaped = "\(aPlusSomething.asURL.path.replacing("+", with: "%2B"))"
+      #if os(Windows)
+      let urlWithPlusEscaped = try XCTUnwrap(URL(string: "file:///\(pathWithPlusEscaped)"))
+      #else
+      let urlWithPlusEscaped = try XCTUnwrap(URL(string: "file://\(pathWithPlusEscaped)"))
+      #endif
       let arguments = try await unwrap(
         buildSystemManager.buildSettingsInferredFromMainFile(
-          for: DocumentURI(URL(string: "file://\(aPlusSomething.asURL.path.replacing("+", with: "%2B"))")!),
+          for: DocumentURI(urlWithPlusEscaped),
           language: .swift
         )
       )
@@ -787,6 +793,10 @@ final class SwiftPMBuildSystemTests: XCTestCase {
   }
 
   func testPluginArgs() async throws {
+    #if os(Windows)
+    // TODO: Enable this test once https://github.com/swiftlang/swift-foundation/issues/973 is fixed
+    try XCTSkipIf(true, "https://github.com/swiftlang/swift-foundation/issues/973")
+    #endif
     try await withTestScratchDir { tempDir in
       try localFileSystem.createFiles(
         root: tempDir,
diff --git a/Tests/DiagnoseTests/DiagnoseTests.swift b/Tests/DiagnoseTests/DiagnoseTests.swift
index b3b76743..273823a4 100644
--- a/Tests/DiagnoseTests/DiagnoseTests.swift
+++ b/Tests/DiagnoseTests/DiagnoseTests.swift
@@ -25,7 +25,7 @@ import struct TSCBasic.AbsolutePath
 private let sdkArg: String = {
   if let sdk = defaultSDKPath {
     return """
-      "-sdk", "\(sdk)",
+      "-sdk", "\(sdk.replacing(#"\"#, with: #"\\"#))"
       """
   } else {
     return ""
@@ -36,7 +36,7 @@ private let sdkArg: String = {
 /// YAML. Otherwise, return an empty string.
 private let sdkArgs: [String] = {
   if let sdk = defaultSDKPath {
-    return ["-sdk", "\(sdk)"]
+    return ["-sdk", sdk]
   } else {
     return []
   }
@@ -254,7 +254,7 @@ private func assertReduceSourceKitD(
 
     let request =
       request
-      .replacingOccurrences(of: "$FILE", with: testFilePath)
+      .replacingOccurrences(of: "$FILE", with: testFilePath.replacing(#"\"#, with: #"\\"#))
       .replacingOccurrences(of: "$OFFSET", with: String(markerOffset))
 
     let requestInfo = try RequestInfo(request: request)
diff --git a/Tests/SKSupportTests/AsyncUtilsTests.swift b/Tests/SKSupportTests/AsyncUtilsTests.swift
index 7edc7fe0..41af3d94 100644
--- a/Tests/SKSupportTests/AsyncUtilsTests.swift
+++ b/Tests/SKSupportTests/AsyncUtilsTests.swift
@@ -16,6 +16,10 @@ import SKTestSupport
 import SwiftExtensions
 import XCTest
 
+#if os(Windows)
+import WinSDK
+#endif
+
 final class AsyncUtilsTests: XCTestCase {
   func testWithTimeout() async throws {
     let expectation = self.expectation(description: "withTimeout body finished")
@@ -34,7 +38,13 @@ final class AsyncUtilsTests: XCTestCase {
   func testWithTimeoutReturnsImmediatelyEvenIfBodyDoesntCooperateInCancellation() async throws {
     let start = Date()
     await assertThrowsError(
-      try await withTimeout(.seconds(0.1)) { sleep(10) }
+      try await withTimeout(.seconds(0.1)) {
+        #if os(Windows)
+        Sleep(10_000 /*ms*/)
+        #else
+        sleep(10 /*s*/)
+        #endif
+      }
     ) { error in
       XCTAssert(error is TimeoutError, "Received unexpected error \(error)")
     }
diff --git a/Tests/SKSupportTests/ProcessRunTests.swift b/Tests/SKSupportTests/ProcessRunTests.swift
index 83c81b13..d9b06978 100644
--- a/Tests/SKSupportTests/ProcessRunTests.swift
+++ b/Tests/SKSupportTests/ProcessRunTests.swift
@@ -17,23 +17,32 @@ import XCTest
 import struct TSCBasic.AbsolutePath
 import class TSCBasic.Process
 
-final class ProcessLaunchTests: XCTestCase {
+final class ProcessRunTests: XCTestCase {
   func testWorkingDirectory() async throws {
-    let project = try await MultiFileTestProject(files: [
-      "parent dir/subdir A/a.txt": "",
-      "parent dir/subdir B/b.txt": "",
-      "parent dir/subdir C/c.txt": "",
-    ])
+    try await withTestScratchDir { tempDir in
+      let workingDir = tempDir.appending(component: "working-dir")
+      try FileManager.default.createDirectory(at: workingDir.asURL, withIntermediateDirectories: true)
 
-    let ls = try await unwrap(findTool(name: "ls"))
+      #if os(Windows)
+      // On Windows, Python 3 gets installed as python.exe
+      let pythonName = "python"
+      #else
+      let pythonName = "python3"
+      #endif
+      let python = try await unwrap(findTool(name: pythonName))
 
-    let result = try await Process.run(
-      arguments: [ls.path, "subdir A", "subdir B"],
-      workingDirectory: AbsolutePath(validating: project.scratchDirectory.path).appending(component: "parent dir")
-    )
-    let stdout = try unwrap(String(bytes: result.output.get(), encoding: .utf8))
-    XCTAssert(stdout.contains("a.txt"), "Directory did not contain a.txt:\n\(stdout)")
-    XCTAssert(stdout.contains("b.txt"), "Directory did not contain b.txt:\n\(stdout)")
-    XCTAssert(!stdout.contains("c.txt"), "Directory contained c.txt:\n\(stdout)")
+      let pythonFile = tempDir.appending(component: "show-cwd.py")
+      try """
+      import os
+      print(os.getcwd(), end='')
+      """.write(to: pythonFile.asURL, atomically: true, encoding: .utf8)
+
+      let result = try await Process.run(
+        arguments: [python.path, pythonFile.pathString],
+        workingDirectory: workingDir
+      )
+      let stdout = try unwrap(String(bytes: result.output.get(), encoding: .utf8))
+      XCTAssertEqual(stdout, workingDir.pathString)
+    }
   }
 }
diff --git a/Tests/SourceKitLSPTests/CodeActionTests.swift b/Tests/SourceKitLSPTests/CodeActionTests.swift
index c0afa178..1544696a 100644
--- a/Tests/SourceKitLSPTests/CodeActionTests.swift
+++ b/Tests/SourceKitLSPTests/CodeActionTests.swift
@@ -1119,11 +1119,12 @@ final class CodeActionTests: XCTestCase {
     ranges: [(String, String)] = [],
     exhaustive: Bool = true,
     expected: (_ uri: DocumentURI, _ positions: DocumentPositions) -> [CodeAction],
+    testName: String = #function,
     file: StaticString = #filePath,
     line: UInt = #line
   ) async throws {
     let testClient = try await TestSourceKitLSPClient(capabilities: clientCapabilitiesWithCodeActionSupport)
-    let uri = DocumentURI(for: .swift)
+    let uri = DocumentURI(for: .swift, testName: testName)
     let positions = testClient.openDocument(markedText, uri: uri)
 
     var ranges = ranges
diff --git a/Tests/SourceKitLSPTests/IndexTests.swift b/Tests/SourceKitLSPTests/IndexTests.swift
index 7960b17e..89e57ea6 100644
--- a/Tests/SourceKitLSPTests/IndexTests.swift
+++ b/Tests/SourceKitLSPTests/IndexTests.swift
@@ -99,6 +99,10 @@ final class IndexTests: XCTestCase {
   }
 
   func testIndexShutdown() async throws {
+    #if os(Windows)
+    // TODO: Fix this test (https://github.com/swiftlang/sourcekit-lsp/issues/1750)
+    try XCTSkipIf(true, "https://github.com/swiftlang/sourcekit-lsp/issues/1750")
+    #endif
 
     func listdir(_ url: URL) throws -> [URL] {
       try FileManager.default.contentsOfDirectory(at: url, includingPropertiesForKeys: nil)
diff --git a/Tests/SourceKitLSPTests/LocalClangTests.swift b/Tests/SourceKitLSPTests/LocalClangTests.swift
index f6b36d08..d89dcd93 100644
--- a/Tests/SourceKitLSPTests/LocalClangTests.swift
+++ b/Tests/SourceKitLSPTests/LocalClangTests.swift
@@ -245,6 +245,10 @@ final class LocalClangTests: XCTestCase {
   }
 
   func testClangModules() async throws {
+    #if os(Windows)
+    // TODO: Enable this test once https://github.com/swiftlang/swift-foundation/issues/973 is fixed
+    try XCTSkipIf(true, "https://github.com/swiftlang/swift-foundation/issues/973")
+    #endif
     let project = try await MultiFileTestProject(
       files: [
         "ClangModuleA.h": """
diff --git a/Tests/SourceKitLSPTests/SwiftInterfaceTests.swift b/Tests/SourceKitLSPTests/SwiftInterfaceTests.swift
index c898d808..fce7ae9f 100644
--- a/Tests/SourceKitLSPTests/SwiftInterfaceTests.swift
+++ b/Tests/SourceKitLSPTests/SwiftInterfaceTests.swift
@@ -65,7 +65,7 @@ final class SwiftInterfaceTests: XCTestCase {
       uri: project.fileURI,
       position: project.positions["1️⃣"],
       testClient: project.testClient,
-      swiftInterfaceFile: "/Swift.String.swiftinterface",
+      swiftInterfaceFile: "Swift.String.swiftinterface",
       linePrefix: "@frozen public struct String"
     )
     // Test stdlib with two submodules
@@ -73,7 +73,7 @@ final class SwiftInterfaceTests: XCTestCase {
       uri: project.fileURI,
       position: project.positions["2️⃣"],
       testClient: project.testClient,
-      swiftInterfaceFile: "/Swift.Math.Integers.swiftinterface",
+      swiftInterfaceFile: "Swift.Math.Integers.swiftinterface",
       linePrefix: "@frozen public struct Int"
     )
     // Test concurrency
@@ -81,7 +81,7 @@ final class SwiftInterfaceTests: XCTestCase {
       uri: project.fileURI,
       position: project.positions["3️⃣"],
       testClient: project.testClient,
-      swiftInterfaceFile: "/_Concurrency.swiftinterface",
+      swiftInterfaceFile: "_Concurrency.swiftinterface",
       linePrefix: "@inlinable public func withTaskGroup"
     )
   }
@@ -118,7 +118,7 @@ final class SwiftInterfaceTests: XCTestCase {
         )
       )
     let location = try XCTUnwrap(response?.locations?.only)
-    XCTAssertTrue(location.uri.pseudoPath.hasSuffix("/MyLibrary.swiftinterface"))
+    XCTAssertTrue(location.uri.pseudoPath.hasSuffix("MyLibrary.swiftinterface"))
     let fileContents = try XCTUnwrap(location.uri.fileURL.flatMap({ try String(contentsOf: $0, encoding: .utf8) }))
     XCTAssertTrue(
       fileContents.contains(
@@ -152,7 +152,7 @@ final class SwiftInterfaceTests: XCTestCase {
       uri: uri,
       position: positions["1️⃣"],
       testClient: testClient,
-      swiftInterfaceFile: "/Swift.Collection.Array.swiftinterface",
+      swiftInterfaceFile: "Swift.Collection.Array.swiftinterface",
       linePrefix: "@inlinable public func filter(_ isIncluded: (Element) throws -> Bool) rethrows -> [Element]"
     )
   }
@@ -171,7 +171,7 @@ final class SwiftInterfaceTests: XCTestCase {
       uri: project.fileURI,
       position: project.positions["1️⃣"],
       testClient: project.testClient,
-      swiftInterfaceFile: "/Swift.Collection.Array.swiftinterface",
+      swiftInterfaceFile: "Swift.Collection.Array.swiftinterface",
       linePrefix: "@inlinable public func filter(_ isIncluded: (Element) throws -> Bool) rethrows -> [Element]"
     )
   }
@@ -192,8 +192,9 @@ private func assertSystemSwiftInterface(
     )
   )
   let location = try XCTUnwrap(definition?.locations?.only)
-  XCTAssertTrue(
-    location.uri.pseudoPath.hasSuffix(swiftInterfaceFile),
+  XCTAssertEqual(
+    location.uri.fileURL?.lastPathComponent,
+    swiftInterfaceFile,
     "Path was: '\(location.uri.pseudoPath)'",
     line: line
   )