diff --git a/clang-tools-extra/clangd/unittests/CompileCommandsTests.cpp b/clang-tools-extra/clangd/unittests/CompileCommandsTests.cpp
--- a/clang-tools-extra/clangd/unittests/CompileCommandsTests.cpp
+++ b/clang-tools-extra/clangd/unittests/CompileCommandsTests.cpp
@@ -79,6 +79,13 @@
     EXPECT_THAT(Cmd, Not(Contains(Stripped)));
 }
 
+TEST(CommandMangler, StripShowIncludes) {
+  auto Mangler = CommandMangler::forTests();
+  std::vector<std::string> Cmd = {"clang-cl", "/showIncludes", "foo.cc"};
+  Mangler.adjust(Cmd);
+  EXPECT_THAT(Cmd, Not(Contains("/showIncludes")));
+}
+
 TEST(CommandMangler, ClangPath) {
   auto Mangler = CommandMangler::forTests();
   Mangler.ClangPath = testPath("fake/clang");
diff --git a/clang/lib/Tooling/ArgumentsAdjusters.cpp b/clang/lib/Tooling/ArgumentsAdjusters.cpp
--- a/clang/lib/Tooling/ArgumentsAdjusters.cpp
+++ b/clang/lib/Tooling/ArgumentsAdjusters.cpp
@@ -98,7 +98,7 @@
       StringRef Arg = Args[i];
       // All dependency-file options begin with -M. These include -MM,
       // -MF, -MG, -MP, -MT, -MQ, -MD, and -MMD.
-      if (!Arg.startswith("-M")) {
+      if (!Arg.startswith("-M") && Arg != "/showIncludes") {
         AdjustedArgs.push_back(Args[i]);
         continue;
       }