Index: lib/Driver/ToolChains/Gnu.cpp
===================================================================
--- lib/Driver/ToolChains/Gnu.cpp
+++ lib/Driver/ToolChains/Gnu.cpp
@@ -629,6 +629,18 @@
       ppc::getPPCAsmModeForCPU(getCPUName(Args, getToolChain().getTriple())));
     break;
   }
+  case llvm::Triple::riscv32:
+  case llvm::Triple::riscv64: {
+    StringRef ABIName = riscv::getRISCVABI(Args, getToolChain().getTriple());
+    CmdArgs.push_back("-mabi");
+    CmdArgs.push_back(ABIName.data());
+    if (const Arg *A = Args.getLastArg(options::OPT_march_EQ)) {
+      StringRef MArch = A->getValue();
+      CmdArgs.push_back("-march");
+      CmdArgs.push_back(MArch.data());
+    }
+    break;
+  }
   case llvm::Triple::sparc:
   case llvm::Triple::sparcel: {
     CmdArgs.push_back("-32");
Index: test/Driver/Inputs/multilib_riscv_linux_sdk/riscv64-unknown-linux-gnu/bin/as
===================================================================
--- /dev/null
+++ test/Driver/Inputs/multilib_riscv_linux_sdk/riscv64-unknown-linux-gnu/bin/as
@@ -0,0 +1 @@
+#!/bin/true
Index: test/Driver/riscv-gnutools.c
===================================================================
--- /dev/null
+++ test/Driver/riscv-gnutools.c
@@ -0,0 +1,14 @@
+// Check gnutools are invoked with propagated values for -mabi and -march.
+
+// RUN: %clang -target riscv32-linux-unknown-elf -fno-integrated-as \
+// RUN: --gcc-toolchain=%S/Inputs/multilib_riscv_linux_sdk \
+// RUN: --sysroot=%S/Inputs/multilib_riscv_linux_sdk/sysroot %s -### \
+// RUN: 2>&1 | FileCheck -check-prefix=MABI-ILP32 %s
+// RUN: %clang -target riscv32-linux-unknown-elf -fno-integrated-as \
+// RUN: -march=rv32g --gcc-toolchain=%S/Inputs/multilib_riscv_linux_sdk \
+// RUN: --sysroot=%S/Inputs/multilib_riscv_linux_sdk/sysroot %s -### \
+// RUN: 2>&1 | FileCheck -check-prefix=MABI-ILP32-MARCH-G %s
+
+// MABI-ILP32: "{{.*}}/Inputs/multilib_riscv_linux_sdk/lib/gcc/riscv64-unknown-linux-gnu/7.2.0/../../../../riscv64-unknown-linux-gnu/bin{{/|\\\\}}as" "-mabi" "ilp32"
+// MABI-ILP32-MARCH-G: "{{.*}}/Inputs/multilib_riscv_linux_sdk/lib/gcc/riscv64-unknown-linux-gnu/7.2.0/../../../../riscv64-unknown-linux-gnu/bin{{/|\\\\}}as" "-mabi" "ilp32" "-march" "rv32g"
+