Index: lld/COFF/DriverUtils.cpp
===================================================================
--- lld/COFF/DriverUtils.cpp
+++ lld/COFF/DriverUtils.cpp
@@ -360,22 +360,20 @@
   return OS.str();
 }
 
-static Expected<std::unique_ptr<MemoryBuffer>>
+static std::unique_ptr<MemoryBuffer>
 createManifestXmlWithInternalMt(std::string &DefaultXml) {
   std::unique_ptr<MemoryBuffer> DefaultXmlCopy =
       MemoryBuffer::getMemBufferCopy(DefaultXml);
 
   windows_manifest::WindowsManifestMerger Merger;
   if (auto E = Merger.merge(*DefaultXmlCopy.get()))
-    return std::move(E);
+    fatal(E, "internal manifest tool failed on default xml");
 
   for (StringRef Filename : Config->ManifestInput) {
     std::unique_ptr<MemoryBuffer> Manifest =
         check(MemoryBuffer::getFile(Filename));
-    if (auto E = Merger.merge(*Manifest.get())) {
-      warn("internal manifest tool failed on file " + Filename);
-      return std::move(E);
-    }
+    if (auto E = Merger.merge(*Manifest.get()))
+      fatal(E, "internal manifest tool failed on file " + Filename);
   }
 
   return Merger.getMergedManifest();
@@ -385,7 +383,8 @@
 createManifestXmlWithExternalMt(std::string &DefaultXml) {
   const Triple HostTriple(Triple::normalize(LLVM_HOST_TRIPLE));
   if (!HostTriple.isOSWindows())
-    fatal("manifest ignored because no external manifest tool available");
+    fatal("external mt.exe is not available because this is not a Windows "
+          "system");
   // Create the default manifest file as a temporary file.
   TemporaryFile Default("defaultxml", "manifest");
   std::error_code EC;
@@ -418,22 +417,13 @@
   if (Config->ManifestInput.empty())
     return DefaultXml;
 
-  // If manifest files are supplied by the user using /MANIFESTINPUT
-  // option, we need to merge them with the default manifest. If libxml2
-  // is enabled, we may merge them with LLVM's own library.
-  Expected<std::unique_ptr<MemoryBuffer>> OutputBufferOrError =
-      createManifestXmlWithInternalMt(DefaultXml);
-  if (OutputBufferOrError)
-    return OutputBufferOrError.get()->getBuffer();
-  // Using built-in library failed, possibly because libxml2 is not installed.
-  // Shell out to mt.exe instead.
-  handleAllErrors(OutputBufferOrError.takeError(),
-                  [&](ErrorInfoBase &EIB) {
-                    warn("error with internal manifest tool: " + EIB.message());
-                  });
   std::unique_ptr<MemoryBuffer> OutputBuffer;
-  OutputBuffer = createManifestXmlWithExternalMt(DefaultXml);
-  return OutputBuffer->getBuffer();
+  if (windows_manifest::isAvailable())
+    OutputBuffer = createManifestXmlWithInternalMt(DefaultXml);
+  else
+    OutputBuffer = createManifestXmlWithExternalMt(DefaultXml);
+
+  return OutputBuffer.get()->getBuffer();
 }
 
 static std::unique_ptr<MemoryBuffer>
Index: lld/test/COFF/manifestinput-error.test
===================================================================
--- /dev/null
+++ lld/test/COFF/manifestinput-error.test
@@ -0,0 +1,10 @@
+# UNSUPPORTED: manifest_tool
+# UNSUPPORTED: libxml2
+
+# RUN: yaml2obj %p/Inputs/ret42.yaml > %t.obj
+# RUN: not lld-link /out:%t.exe /entry:main \
+# RUN:   /manifest:embed \
+# RUN:   /manifestuac:"level='requireAdministrator'" \
+# RUN:   /manifestinput:%p/Inputs/manifestinput.test %t.obj 2>&1 | FileCheck %s
+
+# CHECK: error: external mt.exe is not available because this is not a Windows system
Index: lld/test/COFF/manifestinput-nowarning.test
===================================================================
--- /dev/null
+++ lld/test/COFF/manifestinput-nowarning.test
@@ -0,0 +1,11 @@
+# UNSUPPORTED: libxml2
+# REQUIRES: manifest_tool
+
+# RUN: yaml2obj %p/Inputs/ret42.yaml > %t.obj
+# RUN: lld-link /out:%t.exe /entry:main \
+# RUN:   /manifest:embed \
+# RUN:   /manifestuac:"level='requireAdministrator'" \
+# RUN:   /manifestinput:%p/Inputs/manifestinput.test %t.obj | \
+# RUN:	 FileCheck -allow-empty %s
+
+# CHECK-NOT: warning: error with internal manifest tool: no libxml2
Index: lld/test/lit.cfg
===================================================================
--- lld/test/lit.cfg
+++ lld/test/lit.cfg
@@ -270,3 +270,6 @@
 if (lit.util.which('cvtres', config.environment['PATH'])) or \
  (config.llvm_libxml2_enabled == "1"):
     config.available_features.add('manifest_tool')
+
+if (config.llvm_libxml2_enabled == "1"):
+    config.available_features.add('libxml2')
\ No newline at end of file
Index: llvm/include/llvm/WindowsManifest/WindowsManifestMerger.h
===================================================================
--- llvm/include/llvm/WindowsManifest/WindowsManifestMerger.h
+++ llvm/include/llvm/WindowsManifest/WindowsManifestMerger.h
@@ -35,6 +35,8 @@
 
 namespace windows_manifest {
 
+bool isAvailable();
+
 class WindowsManifestError : public ErrorInfo<WindowsManifestError, ECError> {
 public:
   static char ID;
Index: llvm/lib/WindowsManifest/WindowsManifestMerger.cpp
===================================================================
--- llvm/lib/WindowsManifest/WindowsManifestMerger.cpp
+++ llvm/lib/WindowsManifest/WindowsManifestMerger.cpp
@@ -682,6 +682,8 @@
                     : nullptr;
 }
 
+bool windows_manifest::isAvailable() { return true; }
+
 #else
 
 WindowsManifestMerger::WindowsManifestMergerImpl::~WindowsManifestMergerImpl() {
@@ -697,6 +699,8 @@
   return nullptr;
 }
 
+bool windows_manifest::isAvailable() { return false; }
+
 #endif
 
 WindowsManifestMerger::WindowsManifestMerger()