--- a/clang/lib/Driver/ToolChains/MinGW.cpp
+++ b/clang/lib/Driver/ToolChains/MinGW.cpp
@@ -334,8 +334,9 @@
 
 // Simplified from Generic_GCC::GCCInstallationDetector::ScanLibDirForGCCTriple.
 static bool findGccVersion(StringRef LibDir, std::string &GccLibDir,
-                           std::string &Ver) {
-  auto Version = toolchains::Generic_GCC::GCCVersion::Parse("0.0.0");
+                           std::string &Ver,
+                           toolchains::Generic_GCC::GCCVersion &Version) {
+  Version = toolchains::Generic_GCC::GCCVersion::Parse("0.0.0");
   std::error_code EC;
   for (llvm::sys::fs::directory_iterator LI(LibDir, EC), LE; !EC && LI != LE;
        LI = LI.increment(EC)) {
@@ -366,7 +367,7 @@
     for (StringRef CandidateSysroot : SubdirNames) {
       llvm::SmallString<1024> LibDir(Base);
       llvm::sys::path::append(LibDir, CandidateLib, "gcc", CandidateSysroot);
-      if (findGccVersion(LibDir, GccLibDir, Ver)) {
+      if (findGccVersion(LibDir, GccLibDir, Ver, GccVer)) {
         SubdirName = std::string(CandidateSysroot);
         return;
       }
@@ -433,6 +434,11 @@
   getFilePaths().push_back(GccLibDir);
   getFilePaths().push_back(
       (Base + SubdirName + llvm::sys::path::get_separator() + "lib").str());
+
+  // Gentoo
+  getFilePaths().push_back(
+      (Base + SubdirName + llvm::sys::path::get_separator() + "mingw/lib").str());
+
   getFilePaths().push_back(Base + "lib");
   // openSUSE
   getFilePaths().push_back(Base + SubdirName + "/sys-root/mingw/lib");
@@ -587,6 +593,11 @@
   addSystemInclude(DriverArgs, CC1Args,
                    Base + SubdirName + llvm::sys::path::get_separator() +
                        "include");
+
+  // Gentoo
+  addSystemInclude(DriverArgs, CC1Args,
+                   Base + SubdirName + llvm::sys::path::get_separator() + "usr/include");
+
   addSystemInclude(DriverArgs, CC1Args, Base + "include");
 }
 
@@ -614,7 +625,7 @@
   }
 
   case ToolChain::CST_Libstdcxx:
-    llvm::SmallVector<llvm::SmallString<1024>, 4> CppIncludeBases;
+    llvm::SmallVector<llvm::SmallString<1024>, 7> CppIncludeBases;
     CppIncludeBases.emplace_back(Base);
     llvm::sys::path::append(CppIncludeBases[0], SubdirName, "include", "c++");
     CppIncludeBases.emplace_back(Base);
@@ -624,6 +635,15 @@
     llvm::sys::path::append(CppIncludeBases[2], "include", "c++", Ver);
     CppIncludeBases.emplace_back(GccLibDir);
     llvm::sys::path::append(CppIncludeBases[3], "include", "c++");
+    CppIncludeBases.emplace_back(GccLibDir);
+    llvm::sys::path::append(CppIncludeBases[4], "include",
+                            "g++-v" + GccVer.Text);
+    CppIncludeBases.emplace_back(GccLibDir);
+    llvm::sys::path::append(CppIncludeBases[5], "include",
+                            "g++-v" + GccVer.MajorStr + "." + GccVer.MinorStr);
+    CppIncludeBases.emplace_back(GccLibDir);
+    llvm::sys::path::append(CppIncludeBases[6], "include",
+                            "g++-v" + GccVer.MajorStr);
     for (auto &CppIncludeBase : CppIncludeBases) {
       addSystemInclude(DriverArgs, CC1Args, CppIncludeBase);
       CppIncludeBase += Slash;
--- a/clang/lib/Driver/ToolChains/MinGW.h
+++ b/clang/lib/Driver/ToolChains/MinGW.h
@@ -103,6 +103,7 @@
 
   std::string Base;
   std::string GccLibDir;
+  clang::driver::toolchains::Generic_GCC::GCCVersion GccVer;
   std::string Ver;
   std::string SubdirName;
   mutable std::unique_ptr<tools::gcc::Preprocessor> Preprocessor;