diff --git a/.gitignore b/.gitignore
index 2e3f3e3..1f07c20 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
+.*.sw[nop]
 .DS_Store
 xcuserdata
 *.xcscmblueprint
diff --git a/CMakeLists.txt b/CMakeLists.txt
index aa705ba..e16cd14 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -8,6 +8,8 @@
         LANGUAGES
           C)
 
+option(BUILD_SHARED_LIBS "Build shared libraries" ON)
+
 option(XCTEST_PATH_TO_LIBDISPATCH_SOURCE "Path to libdispatch source" "")
 option(XCTEST_PATH_TO_LIBDISPATCH_BUILD "Path to libdispatch build" "")
 
@@ -127,11 +129,12 @@
                     "Copying swiftmodule/swiftdoc to build directory")
 
 if(EXISTS ${LLVM_MAIN_SRC_DIR}/utils/lit/lit.py)
-  set(LIT_COMMAND "${PYTHON_EXECUTABLE};${LLVM_MAIN_SRC_DIR}/utils/lit/lit.py"
+  set(LIT_COMMAND "${LLVM_MAIN_SRC_DIR}/utils/lit/lit.py"
       CACHE STRING "command used to spawn llvm-lit")
 else()
   find_program(LIT_COMMAND NAMES llvm-lit lit.py lit)
 endif()
+find_package(PythonInterp)
 add_custom_target(check-xctest
                   COMMAND
                   ${CMAKE_COMMAND} -E env
@@ -142,7 +145,7 @@
                     LIBDISPATCH_BUILD_DIR=${XCTEST_PATH_TO_LIBDISPATCH_BUILD}
                     LIBDISPATCH_OVERLAY_DIR=${XCTEST_PATH_TO_LIBDISPATCH_BUILD}/src/swift
                     SWIFT_EXEC=${CMAKE_SWIFT_COMPILER}
-                    ${LIT_COMMAND} -sv ${CMAKE_SOURCE_DIR}/Tests/Functional
+                    ${PYTHON_EXECUTABLE} ${LIT_COMMAND} -sv ${CMAKE_SOURCE_DIR}/Tests/Functional
                   COMMENT
                     "Running XCTest functional test suite"
                   DEPENDS
diff --git a/Sources/XCTest/Public/Asynchronous/XCTWaiter.swift b/Sources/XCTest/Public/Asynchronous/XCTWaiter.swift
index 0a404c5..13a232f 100644
--- a/Sources/XCTest/Public/Asynchronous/XCTWaiter.swift
+++ b/Sources/XCTest/Public/Asynchronous/XCTWaiter.swift
@@ -217,9 +217,9 @@
         self.manager = manager
 
         // Begin the core wait loop.
-        let timeoutTimestamp = CFAbsoluteTimeGetCurrent() + timeout
+        let timeoutTimestamp = Date.timeIntervalSinceReferenceDate + timeout
         while !isFinished {
-            let remaining = timeoutTimestamp - CFAbsoluteTimeGetCurrent()
+            let remaining = timeoutTimestamp - Date.timeIntervalSinceReferenceDate
             if remaining <= 0 {
                 break
             }
@@ -367,7 +367,11 @@
 
     func cancelPrimitiveWait() {
         guard let runLoop = runLoop else { return }
+#if os(Windows)
+        runLoop._stop()
+#else
         CFRunLoopStop(runLoop.getCFRunLoop())
+#endif
     }
 }
 
diff --git a/Tests/Functional/Asynchronous/Expectations/main.swift b/Tests/Functional/Asynchronous/Expectations/main.swift
index d7ec8e9..0fce781 100644
--- a/Tests/Functional/Asynchronous/Expectations/main.swift
+++ b/Tests/Functional/Asynchronous/Expectations/main.swift
@@ -216,11 +216,11 @@
             bar.fulfill()
         }
 
-        let start = CFAbsoluteTimeGetCurrent()
+        let start = Date.timeIntervalSinceReferenceDate
         waitForExpectations(timeout: 0.5)
 
         // Make sure we actually waited long enough.
-        XCTAssertGreaterThanOrEqual(CFAbsoluteTimeGetCurrent() - start, 0.5)
+        XCTAssertGreaterThanOrEqual(Date.timeIntervalSinceReferenceDate - start, 0.5)
     }
 
 // CHECK: Test Case 'ExpectationsTestCase.test_combiningInverseAndStandardExpectationsFailWithTimeout' started at \d+-\d+-\d+ \d+:\d+:\d+\.\d+
@@ -231,11 +231,11 @@
         foo.isInverted = true
         expectation(description: "bar")
 
-        let start = CFAbsoluteTimeGetCurrent()
+        let start = Date.timeIntervalSinceReferenceDate
         waitForExpectations(timeout: 0.5)
 
         // Make sure we actually waited long enough.
-        XCTAssertGreaterThanOrEqual(CFAbsoluteTimeGetCurrent() - start, 0.5)
+        XCTAssertGreaterThanOrEqual(Date.timeIntervalSinceReferenceDate - start, 0.5)
     }
 
 // CHECK: Test Case 'ExpectationsTestCase.test_combiningInverseAndStandardExpectationsFailWithInverseFulfillment' started at \d+-\d+-\d+ \d+:\d+:\d+\.\d+
@@ -269,9 +269,9 @@
             c.fulfill()
         }
 
-        start = CFAbsoluteTimeGetCurrent()
+        start = Date.timeIntervalSinceReferenceDate
         wait(for: [a, b, c], timeout: 0.2, enforceOrder: true)
-        XCTAssertGreaterThanOrEqual(CFAbsoluteTimeGetCurrent() - start, 0.2)
+        XCTAssertGreaterThanOrEqual(Date.timeIntervalSinceReferenceDate - start, 0.2)
 
         a = XCTestExpectation(description: "a")
         a.isInverted = true
@@ -282,9 +282,9 @@
             c.fulfill()
         }
 
-        start = CFAbsoluteTimeGetCurrent()
+        start = Date.timeIntervalSinceReferenceDate
         wait(for: [b, a, c], timeout: 0.2, enforceOrder: true)
-        XCTAssertGreaterThanOrEqual(CFAbsoluteTimeGetCurrent() - start, 0.2)
+        XCTAssertGreaterThanOrEqual(Date.timeIntervalSinceReferenceDate - start, 0.2)
 
         a = XCTestExpectation(description: "a")
         a.isInverted = true
@@ -295,9 +295,9 @@
             c.fulfill()
         }
 
-        start = CFAbsoluteTimeGetCurrent()
+        start = Date.timeIntervalSinceReferenceDate
         wait(for: [b, c, a], timeout: 0.2, enforceOrder: true)
-        XCTAssertGreaterThanOrEqual(CFAbsoluteTimeGetCurrent() - start, 0.2)
+        XCTAssertGreaterThanOrEqual(Date.timeIntervalSinceReferenceDate - start, 0.2)
     }
 
     // PRAGMA MARK: - Counted Expectations
@@ -362,9 +362,9 @@
             }
         }
 
-        let start = CFAbsoluteTimeGetCurrent()
+        let start = Date.timeIntervalSinceReferenceDate
         let result = outerWaiter.wait(for: [outerExpectation], timeout: 0.1)
-        let durationOfOuterWait = CFAbsoluteTimeGetCurrent() - start
+        let durationOfOuterWait = Date.timeIntervalSinceReferenceDate - start
         XCTAssertEqual(result, .timedOut)
 
         // The theoretical best-case duration in the current implementation is:
@@ -383,7 +383,7 @@
         var outerExpectationFulfillTime = CFAbsoluteTime(0)
         RunLoop.main.perform {
             RunLoop.main.perform {
-                outerExpectationFulfillTime = CFAbsoluteTimeGetCurrent()
+                outerExpectationFulfillTime = Date.timeIntervalSinceReferenceDate
                 outerExpectation.fulfill()
             }
             let innerWaiter = XCTWaiter(delegate: self)
@@ -391,10 +391,10 @@
             XCTAssertEqual(innerWaiter.wait(for: [innerExpectation], timeout: 1), .timedOut)
         }
 
-        let start = CFAbsoluteTimeGetCurrent()
+        let start = Date.timeIntervalSinceReferenceDate
         XCTAssertEqual(outerWaiter.wait(for: [outerExpectation], timeout: 1), .completed)
         XCTAssertLessThanOrEqual(outerExpectationFulfillTime - start, 0.1)
-        XCTAssertGreaterThanOrEqual(CFAbsoluteTimeGetCurrent() - start, 1)
+        XCTAssertGreaterThanOrEqual(Date.timeIntervalSinceReferenceDate - start, 1)
     }
 
     // PRAGMA MARK: - Waiter Conveniences
diff --git a/Tests/Functional/lit.cfg b/Tests/Functional/lit.cfg
index 840ad08..9c38ebd 100644
--- a/Tests/Functional/lit.cfg
+++ b/Tests/Functional/lit.cfg
@@ -38,15 +38,21 @@
 
 built_products_dir = _getenv('BUILT_PRODUCTS_DIR')
 # Force tests to build with -swift-version 4 for now.
-swift_exec = [
-    _getenv('SWIFT_EXEC'),
-    '-swift-version', '4',
-    '-Xlinker', '-rpath',
-    '-Xlinker', built_products_dir,
+swift_exec = [ _getenv('SWIFT_EXEC'), '-swift-version', '4', ]
+if not platform.system() == 'Windows':
+    swift_exec.extend(['-Xlinker', '-rpath', '-Xlinker', built_products_dir,])
+swift_exec.extend([
     '-L', built_products_dir,
     '-I', built_products_dir,
     '-I', os.path.join(built_products_dir, 'swift'),
-]
+])
+
+if platform.system() == 'Linux':
+    swift_exec.extend(['-Xcc', '-DDEPLOYMENT_TARGET_LINUX'])
+elif platform.system() == 'Darwin':
+    swift_exec.extend(['-Xcc', '-DDEPLOYMENT_TARGET_MACOSX'])
+elif platform.system() == 'Windows':
+    swift_exec.extend(['-Xcc', '-DDEPLOYMENT_TARGET_WINDOWS'])
 
 if platform.system() == 'Darwin':
     # On Darwin, we need to make sure swiftc references the
@@ -68,13 +74,14 @@
         '-I', os.path.join(built_products_dir, 'usr', 'local', 'include'),
     ])
 else:
-    # On Linux, we need to jump through extra hoops to link
-    # swift-corelibs-foundation.
+    # We need to jump through extra hoops to link swift-corelibs-foundation.
     foundation_dir = _getenv('FOUNDATION_BUILT_PRODUCTS_DIR')
     core_foundation_dir = _getenv('CORE_FOUNDATION_BUILT_PRODUCTS_DIR')
+    if platform.system() == 'Windows':
+        swift_exec.extend(['-Xlinker', '-nodefaultlib:libcmt'])
+    else:
+        swift_exec.extend(['-Xlinker', '-rpath', '-Xlinker', foundation_dir,])
     swift_exec.extend([
-        '-Xlinker', '-rpath',
-        '-Xlinker', foundation_dir,
         '-L', foundation_dir,
         '-I', foundation_dir,
         '-I', os.path.join(foundation_dir, 'swift'),
@@ -110,7 +117,7 @@
     os.path.dirname(os.path.abspath(__file__)),
     'xctest_checker',
     'xctest_checker.py')
-config.substitutions.append(('%{xctest_checker}', xctest_checker))
+config.substitutions.append(('%{xctest_checker}', '%%{python} %s' % xctest_checker))
 
 # Add Python to run xctest_checker.py tests as part of XCTest tests
 config.substitutions.append( ('%{python}', sys.executable) )