diff --git a/clang/include/clang/Driver/ToolChain.h b/clang/include/clang/Driver/ToolChain.h
--- a/clang/include/clang/Driver/ToolChain.h
+++ b/clang/include/clang/Driver/ToolChain.h
@@ -536,6 +536,10 @@
   /// FIXME: this really belongs on some sort of DeploymentTarget abstraction
   virtual bool hasBlocksRuntime() const { return true; }
 
+  /// Return the sysroot, possibly searching for a default sysroot using
+  /// target-specific logic.
+  virtual std::string computeSysRoot() const;
+
   /// Add the clang cc1 arguments for system include paths.
   ///
   /// This routine is responsible for adding the necessary cc1 arguments to
diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -750,6 +750,10 @@
   return ComputeLLVMTriple(Args, InputType);
 }
 
+std::string ToolChain::computeSysRoot() const {
+  return D.SysRoot;
+}
+
 void ToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
                                           ArgStringList &CC1Args) const {
   // Each toolchain should provide the appropriate include flags.
diff --git a/clang/lib/Driver/ToolChains/Gnu.cpp b/clang/lib/Driver/ToolChains/Gnu.cpp
--- a/clang/lib/Driver/ToolChains/Gnu.cpp
+++ b/clang/lib/Driver/ToolChains/Gnu.cpp
@@ -2846,7 +2846,6 @@
 void
 Generic_GCC::addLibCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
                                    llvm::opt::ArgStringList &CC1Args) const {
-  const std::string& SysRoot = getDriver().SysRoot;
   auto AddIncludePath = [&](std::string Path) {
     std::string IncludePath = DetectLibcxxIncludePath(getVFS(), Path);
     if (IncludePath.empty() || !getVFS().exists(IncludePath))
@@ -2862,6 +2861,7 @@
   // If this is a development, non-installed, clang, libcxx will
   // not be found at ../include/c++ but it likely to be found at
   // one of the following two locations:
+  std::string SysRoot = computeSysRoot();
   if (AddIncludePath(SysRoot + "/usr/local/include/c++"))
     return;
   if (AddIncludePath(SysRoot + "/usr/include/c++"))
diff --git a/clang/lib/Driver/ToolChains/Hurd.h b/clang/lib/Driver/ToolChains/Hurd.h
--- a/clang/lib/Driver/ToolChains/Hurd.h
+++ b/clang/lib/Driver/ToolChains/Hurd.h
@@ -27,8 +27,6 @@
   AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
                             llvm::opt::ArgStringList &CC1Args) const override;
 
-  std::string computeSysRoot() const;
-
   std::string getDynamicLinker(const llvm::opt::ArgList &Args) const override;
 
   void addExtraOpts(llvm::opt::ArgStringList &CmdArgs) const override;
diff --git a/clang/lib/Driver/ToolChains/Hurd.cpp b/clang/lib/Driver/ToolChains/Hurd.cpp
--- a/clang/lib/Driver/ToolChains/Hurd.cpp
+++ b/clang/lib/Driver/ToolChains/Hurd.cpp
@@ -125,13 +125,6 @@
   return new tools::gnutools::Assembler(*this);
 }
 
-std::string Hurd::computeSysRoot() const {
-  if (!getDriver().SysRoot.empty())
-    return getDriver().SysRoot;
-
-  return std::string();
-}
-
 std::string Hurd::getDynamicLinker(const ArgList &Args) const {
   if (getArch() == llvm::Triple::x86)
     return "/lib/ld.so";
diff --git a/clang/lib/Driver/ToolChains/Linux.h b/clang/lib/Driver/ToolChains/Linux.h
--- a/clang/lib/Driver/ToolChains/Linux.h
+++ b/clang/lib/Driver/ToolChains/Linux.h
@@ -42,7 +42,7 @@
   SanitizerMask getSupportedSanitizers() const override;
   void addProfileRTLibs(const llvm::opt::ArgList &Args,
                         llvm::opt::ArgStringList &CmdArgs) const override;
-  virtual std::string computeSysRoot() const;
+  std::string computeSysRoot() const override;
 
   std::string getDynamicLinker(const llvm::opt::ArgList &Args) const override;
 
diff --git a/clang/lib/Driver/ToolChains/MSP430.h b/clang/lib/Driver/ToolChains/MSP430.h
--- a/clang/lib/Driver/ToolChains/MSP430.h
+++ b/clang/lib/Driver/ToolChains/MSP430.h
@@ -44,7 +44,7 @@
   Tool *buildLinker() const override;
 
 private:
-  std::string computeSysRoot() const;
+  std::string computeSysRoot() const override;
 };
 
 } // end namespace toolchains
diff --git a/clang/lib/Driver/ToolChains/RISCVToolchain.h b/clang/lib/Driver/ToolChains/RISCVToolchain.h
--- a/clang/lib/Driver/ToolChains/RISCVToolchain.h
+++ b/clang/lib/Driver/ToolChains/RISCVToolchain.h
@@ -39,7 +39,7 @@
   Tool *buildLinker() const override;
 
 private:
-  std::string computeSysRoot() const;
+  std::string computeSysRoot() const override;
 };
 
 } // end namespace toolchains