Index: cfe/trunk/lib/Lex/HeaderSearch.cpp
===================================================================
--- cfe/trunk/lib/Lex/HeaderSearch.cpp
+++ cfe/trunk/lib/Lex/HeaderSearch.cpp
@@ -1685,11 +1685,10 @@
 
     StringRef Dir = SearchDirs[I].getDir()->getName();
     llvm::SmallString<32> DirPath(Dir.begin(), Dir.end());
-    if (!WorkingDir.empty() && !path::is_absolute(Dir)) {
+    if (!WorkingDir.empty() && !path::is_absolute(Dir))
       fs::make_absolute(WorkingDir, DirPath);
-      path::remove_dots(DirPath, /*remove_dot_dot=*/true);
-      Dir = DirPath;
-    }
+    path::remove_dots(DirPath, /*remove_dot_dot=*/true);
+    Dir = DirPath;
     for (auto NI = path::begin(File), NE = path::end(File),
               DI = path::begin(Dir), DE = path::end(Dir);
          /*termination condition in loop*/; ++NI, ++DI) {
Index: cfe/trunk/unittests/Lex/HeaderSearchTest.cpp
===================================================================
--- cfe/trunk/unittests/Lex/HeaderSearchTest.cpp
+++ cfe/trunk/unittests/Lex/HeaderSearchTest.cpp
@@ -100,5 +100,12 @@
 }
 #endif
 
+TEST_F(HeaderSearchTest, DotDotsWithAbsPath) {
+  addSearchDir("/x/../y/");
+  EXPECT_EQ(Search.suggestPathToFileForDiagnostics("/y/z",
+                                                   /*WorkingDir=*/""),
+            "z");
+}
+
 } // namespace
 } // namespace clang
Index: clang-tools-extra/trunk/unittests/clangd/HeadersTests.cpp
===================================================================
--- clang-tools-extra/trunk/unittests/clangd/HeadersTests.cpp
+++ clang-tools-extra/trunk/unittests/clangd/HeadersTests.cpp
@@ -213,6 +213,11 @@
 TEST_F(HeadersTest, ShortenedInclude) {
   std::string BarHeader = testPath("sub/bar.h");
   EXPECT_EQ(calculate(BarHeader), "\"bar.h\"");
+
+  SearchDirArg = (llvm::Twine("-I") + Subdir + "/..").str();
+  CDB.ExtraClangFlags = {SearchDirArg.c_str()};
+  BarHeader = testPath("sub/bar.h");
+  EXPECT_EQ(calculate(BarHeader), "\"sub/bar.h\"");
 }
 
 TEST_F(HeadersTest, NotShortenedInclude) {