Index: lld/COFF/DriverUtils.cpp
===================================================================
--- lld/COFF/DriverUtils.cpp
+++ lld/COFF/DriverUtils.cpp
@@ -373,19 +373,23 @@
     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);
+      Error Ret = make_error<windows_manifest::WindowsManifestError>(
+          "internal manifest tool failed on file " + Filename + ": " +
+          toString(std::move(E)));
+      return std::move(Ret);
     }
   }
 
   return Merger.getMergedManifest();
 }
 
-static std::unique_ptr<MemoryBuffer>
+static Expected<std::unique_ptr<MemoryBuffer>>
 createManifestXmlWithExternalMt(std::string &DefaultXml) {
   const Triple HostTriple(Triple::normalize(LLVM_HOST_TRIPLE));
   if (!HostTriple.isOSWindows())
-    fatal("manifest ignored because no external manifest tool available");
+    return make_error<windows_manifest::WindowsManifestError>(
+        "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;
@@ -421,19 +425,31 @@
   // 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 =
+  Expected<std::unique_ptr<MemoryBuffer>> InternalOutputBufferOrError =
       createManifestXmlWithInternalMt(DefaultXml);
-  if (OutputBufferOrError)
-    return OutputBufferOrError.get()->getBuffer();
+  if (InternalOutputBufferOrError)
+    return InternalOutputBufferOrError.get()->getBuffer();
   // Using built-in library failed, possibly because libxml2 is not installed.
   // Shell out to mt.exe instead.
-  handleAllErrors(OutputBufferOrError.takeError(),
+  Expected<std::unique_ptr<MemoryBuffer>> ExternalOutputBufferOrError =
+      createManifestXmlWithExternalMt(DefaultXml);
+  if (ExternalOutputBufferOrError) {
+    // Supress internal mt errors when manifest merge succeeds.
+    consumeError(InternalOutputBufferOrError.takeError());
+    return ExternalOutputBufferOrError.get()->getBuffer();
+  }
+
+  // Both attempts to merge manifest have failed.  Display all errors and throw
+  // exception.
+  handleAllErrors(InternalOutputBufferOrError.takeError(),
                   [&](ErrorInfoBase &EIB) {
                     warn("error with internal manifest tool: " + EIB.message());
                   });
-  std::unique_ptr<MemoryBuffer> OutputBuffer;
-  OutputBuffer = createManifestXmlWithExternalMt(DefaultXml);
-  return OutputBuffer->getBuffer();
+  handleAllErrors(ExternalOutputBufferOrError.takeError(),
+                  [&](ErrorInfoBase &EIB) {
+                    warn("error with external manifest tool: " + EIB.message());
+                  });
+  fatal("could not create manifest xml");
 }
 
 static std::unique_ptr<MemoryBuffer>
Index: lld/test/COFF/manifestinput-error.test
===================================================================
--- /dev/null
+++ lld/test/COFF/manifestinput-error.test
@@ -0,0 +1,12 @@
+# 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: lld-link: warning: error with internal manifest tool: no libxml2
+# CHECK: lld-link: warning: error with external manifest tool: external mt.exe is not available because this is not a Windows system
+# CHECK: error: could not create manifest xml
Index: lld/test/COFF/manifestinput-nowarning.test
===================================================================
--- /dev/null
+++ lld/test/COFF/manifestinput-nowarning.test
@@ -0,0 +1,10 @@
+# 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 | FileCheck %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