Index: llvm-toolchain-snapshot_10~+20191020075550+5b8546023f3/clang/lib/Driver/ToolChains/Linux.cpp
===================================================================
--- llvm-toolchain-snapshot_10~+20191020075550+5b8546023f3.orig/clang/lib/Driver/ToolChains/Linux.cpp
+++ llvm-toolchain-snapshot_10~+20191020075550+5b8546023f3/clang/lib/Driver/ToolChains/Linux.cpp
@@ -151,6 +151,10 @@ static std::string getMultiarchTriple(co
     if (D.getVFS().exists(SysRoot + "/lib/powerpc64le-linux-gnu"))
       return "powerpc64le-linux-gnu";
     break;
+  case llvm::Triple::riscv64:
+    if (D.getVFS().exists(SysRoot + "/lib/riscv64-linux-gnu"))
+      return "riscv64-linux-gnu";
+    break;
   case llvm::Triple::sparc:
     if (D.getVFS().exists(SysRoot + "/lib/sparc-linux-gnu"))
       return "sparc-linux-gnu";
@@ -760,6 +764,8 @@ void Linux::AddClangSystemIncludeArgs(co
       "/usr/include/powerpc64-linux-gnu"};
   const StringRef PPC64LEMultiarchIncludeDirs[] = {
       "/usr/include/powerpc64le-linux-gnu"};
+  const StringRef RISCV64MultiarchIncludeDirs[] = {
+      "/usr/include/riscv64-linux-gnu"};
   const StringRef SparcMultiarchIncludeDirs[] = {
       "/usr/include/sparc-linux-gnu"};
   const StringRef Sparc64MultiarchIncludeDirs[] = {
@@ -835,6 +841,9 @@ void Linux::AddClangSystemIncludeArgs(co
   case llvm::Triple::ppc64le:
     MultiarchIncludeDirs = PPC64LEMultiarchIncludeDirs;
     break;
+  case llvm::Triple::riscv64:
+    MultiarchIncludeDirs = RISCV64MultiarchIncludeDirs;
+    break;
   case llvm::Triple::sparc:
     MultiarchIncludeDirs = SparcMultiarchIncludeDirs;
     break;