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 +98,8 @@
       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") && !Arg.startswith("/showIncludes")) {
+      if (!Arg.startswith("-M") && !Arg.startswith("/showIncludes") &&
+          !Arg.startswith("-showIncludes")) {
         AdjustedArgs.push_back(Args[i]);
         continue;
       }
diff --git a/clang/unittests/Tooling/ToolingTest.cpp b/clang/unittests/Tooling/ToolingTest.cpp
--- a/clang/unittests/Tooling/ToolingTest.cpp
+++ b/clang/unittests/Tooling/ToolingTest.cpp
@@ -530,9 +530,11 @@
   EXPECT_TRUE(HasFlag("-w"));
 }
 
-// Check getClangStripDependencyFileAdjuster strips /showIncludes
+// Check getClangStripDependencyFileAdjuster strips /showIncludes and variants
 TEST(ClangToolTest, StripDependencyFileAdjusterShowIncludes) {
-  FixedCompilationDatabase Compilations("/", {"/showIncludes", "-c"});
+  FixedCompilationDatabase Compilations(
+      "/", {"/showIncludes", "/showIncludes:user", "-showIncludes",
+            "-showIncludes:user", "-c"});
 
   ClangTool Tool(Compilations, std::vector<std::string>(1, "/a.cc"));
   Tool.mapVirtualFile("/a.cc", "void a() {}");
@@ -555,34 +557,9 @@
     return llvm::find(FinalArgs, Flag) != FinalArgs.end();
   };
   EXPECT_FALSE(HasFlag("/showIncludes"));
-  EXPECT_TRUE(HasFlag("-c"));
-}
-
-// Check getClangStripDependencyFileAdjuster strips /showIncludes:user
-TEST(ClangToolTest, StripDependencyFileAdjusterShowIncludesUser) {
-  FixedCompilationDatabase Compilations("/", {"/showIncludes:user", "-c"});
-
-  ClangTool Tool(Compilations, std::vector<std::string>(1, "/a.cc"));
-  Tool.mapVirtualFile("/a.cc", "void a() {}");
-
-  std::unique_ptr<FrontendActionFactory> Action(
-      newFrontendActionFactory<SyntaxOnlyAction>());
-
-  CommandLineArguments FinalArgs;
-  ArgumentsAdjuster CheckFlagsAdjuster =
-      [&FinalArgs](const CommandLineArguments &Args, StringRef /*unused*/) {
-        FinalArgs = Args;
-        return Args;
-      };
-  Tool.clearArgumentsAdjusters();
-  Tool.appendArgumentsAdjuster(getClangStripDependencyFileAdjuster());
-  Tool.appendArgumentsAdjuster(CheckFlagsAdjuster);
-  Tool.run(Action.get());
-
-  auto HasFlag = [&FinalArgs](const std::string &Flag) {
-    return llvm::find(FinalArgs, Flag) != FinalArgs.end();
-  };
   EXPECT_FALSE(HasFlag("/showIncludes:user"));
+  EXPECT_FALSE(HasFlag("-showIncludes"));
+  EXPECT_FALSE(HasFlag("-showIncludes:user"));
   EXPECT_TRUE(HasFlag("-c"));
 }