Index: clangd/ClangdServer.cpp
===================================================================
--- clangd/ClangdServer.cpp
+++ clangd/ClangdServer.cpp
@@ -286,6 +286,13 @@
   auto U = URI::parse(Header);
   if (!U)
     return U.takeError();
+
+  auto IncludePath = URI::includePath(*U);
+  if (!IncludePath)
+    return IncludePath.takeError();
+  if (!IncludePath->empty())
+    return HeaderFile{std::move(*IncludePath), /*Verbatim=*/true};
+
   auto Resolved = URI::resolve(*U, HintPath);
   if (!Resolved)
     return Resolved.takeError();
Index: clangd/URI.h
===================================================================
--- clangd/URI.h
+++ clangd/URI.h
@@ -60,6 +60,14 @@
   static llvm::Expected<std::string> resolve(const URI &U,
                                              llvm::StringRef HintPath = "");
 
+  /// Tries to get the include path of the file corresponding to the URI.
+  /// This allows clients to provide their customized include paths.
+  ///
+  /// If the returned string is non-empty, clangd will use it directly when
+  /// doing include insertion; otherwise we will fall back to the clang to
+  /// calculate the include path from the resolved absolute path.
+  static llvm::Expected<std::string> includePath(const URI &U);
+
   friend bool operator==(const URI &LHS, const URI &RHS) {
     return std::tie(LHS.Scheme, LHS.Authority, LHS.Body) ==
            std::tie(RHS.Scheme, RHS.Authority, RHS.Body);
@@ -94,6 +102,13 @@
 
   virtual llvm::Expected<URI>
   uriFromAbsolutePath(llvm::StringRef AbsolutePath) const = 0;
+
+  /// Returns the include path of the file corresponding to the URI, which can
+  /// be #include directly. See URI::resolveIncludePath for details.
+  virtual llvm::Expected<std::string>
+  getIncludePath(const URI& U) const {
+    return "";  // no customized include path for this scheme.
+  }
 };
 
 /// By default, a "file" scheme is supported where URI paths are always absolute
Index: clangd/URI.cpp
===================================================================
--- clangd/URI.cpp
+++ clangd/URI.cpp
@@ -196,5 +196,12 @@
   return S->get()->getAbsolutePath(Uri.Authority, Uri.Body, HintPath);
 }
 
+llvm::Expected<std::string> URI::includePath(const URI &Uri) {
+  auto S = findSchemeByName(Uri.Scheme);
+  if (!S)
+    return S.takeError();
+  return S->get()->getIncludePath(Uri);
+}
+
 } // namespace clangd
 } // namespace clang
Index: unittests/clangd/ClangdTests.cpp
===================================================================
--- unittests/clangd/ClangdTests.cpp
+++ unittests/clangd/ClangdTests.cpp
@@ -961,6 +961,10 @@
                        /*Preferred=*/"<Y.h>", "<Y.h>"));
   EXPECT_TRUE(Inserted(OriginalHeader, PreferredHeader, "\"Y.h\""));
   EXPECT_TRUE(Inserted("<y.h>", PreferredHeader, "\"Y.h\""));
+  auto TestURIHeader = URI::create("/abc/test-root/x/y/z.h", "unittest");
+  EXPECT_TRUE(static_cast<bool>(TestURIHeader));
+  EXPECT_TRUE(Inserted(TestURIHeader->toString(), "", "\"x/y/z.h\""));
+
 
   // Check that includes are sorted.
   const auto Expected = R"cpp(
Index: unittests/clangd/URITests.cpp
===================================================================
--- unittests/clangd/URITests.cpp
+++ unittests/clangd/URITests.cpp
@@ -47,6 +47,10 @@
     return URI(Scheme, /*Authority=*/"",
                AbsolutePath.substr(Pos + llvm::StringRef(TestRoot).size()));
   }
+
+  llvm::Expected<std::string> getIncludePath(const URI &U) const override {
+    return ("\"" + U.body() + "\"").str();
+  }
 };
 
 const char *TestScheme::Scheme = "unittest";