Index: lib/Driver/ToolChains/Gnu.cpp
===================================================================
--- lib/Driver/ToolChains/Gnu.cpp
+++ lib/Driver/ToolChains/Gnu.cpp
@@ -1909,10 +1909,12 @@
       "powerpc64le-linux-gnu", "powerpc64le-unknown-linux-gnu",
       "powerpc64le-suse-linux", "ppc64le-redhat-linux"};
 
-  static const char *const RISCV32LibDirs[] = {"/lib", "/lib32"};
+  static const char *const RISCVLibDirs[] = {"/lib", "/lib32"};
   static const char *const RISCVTriples[] = {"riscv32-unknown-linux-gnu",
-                                             "riscv64-unknown-linux-gnu",
                                              "riscv32-unknown-elf"};
+  static const char *const RISCV64LibDirs[] = {"/lib", "/lib64"};
+  static const char *const RISCV64Triples[] = {"riscv64-unknown-linux-gnu",
+                                               "riscv64-unknown-elf"};
 
   static const char *const SPARCv8LibDirs[] = {"/lib32", "/lib"};
   static const char *const SPARCv8Triples[] = {"sparc-linux-gnu",
@@ -2137,9 +2139,15 @@
     TripleAliases.append(begin(PPC64LETriples), end(PPC64LETriples));
     break;
   case llvm::Triple::riscv32:
-    LibDirs.append(begin(RISCV32LibDirs), end(RISCV32LibDirs));
-    BiarchLibDirs.append(begin(RISCV32LibDirs), end(RISCV32LibDirs));
-    TripleAliases.append(begin(RISCVTriples), end(RISCVTriples));
+    LibDirs.append(begin(RISCVLibDirs), end(RISCVLibDirs));
+    TripleAliases.append(begin(RISCVTriples), end (RISCVTriples));
+    BiarchLibDirs.append(begin(RISCV64LibDirs), end(RISCV64LibDirs));
+    BiarchTripleAliases.append(begin(RISCV64Triples), end(RISCV64Triples));
+    break;
+  case llvm::Triple::riscv64:
+    LibDirs.append(begin(RISCV64LibDirs), end(RISCV64LibDirs));
+    TripleAliases.append(begin(RISCV64Triples), end (RISCV64Triples));
+    BiarchLibDirs.append(begin(RISCVLibDirs), end(RISCVLibDirs));
     BiarchTripleAliases.append(begin(RISCVTriples), end(RISCVTriples));
     break;
   case llvm::Triple::sparc:
Index: test/Driver/Inputs/basic_riscv64_tree/bin/riscv64-unknown-elf-ld
===================================================================
--- /dev/null
+++ test/Driver/Inputs/basic_riscv64_tree/bin/riscv64-unknown-elf-ld
@@ -0,0 +1 @@
+#!/bin/true
Index: test/Driver/riscv64-toolchain.c
===================================================================
--- test/Driver/riscv64-toolchain.c
+++ test/Driver/riscv64-toolchain.c
@@ -3,6 +3,102 @@
 // RUN: %clang %s -### -no-canonical-prefixes -target riscv64 2>&1 | FileCheck -check-prefix=CC1 %s
 // CC1: clang{{.*}} "-cc1" "-triple" "riscv64"
 
+// RUN: %clang %s -### -no-canonical-prefixes \
+// RUN:   -target riscv64-unknown-elf \
+// RUN:   --gcc-toolchain=%S/Inputs/basic_riscv64_tree \
+// RUN:   --sysroot=%S/Inputs/basic_riscv64_tree/riscv64-unknown-elf 2>&1 \
+// RUN:   | FileCheck -check-prefix=C-RV64-BAREMETAL-LP64 %s
+
+// C-RV64-BAREMETAL-LP64: "-fuse-init-array"
+// C-RV64-BAREMETAL-LP64: "{{.*}}Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1/../../../../bin{{/|\\\\}}riscv64-unknown-elf-ld"
+// C-RV64-BAREMETAL-LP64: "--sysroot={{.*}}/Inputs/basic_riscv64_tree/riscv64-unknown-elf"
+// C-RV64-BAREMETAL-LP64: "{{.*}}/Inputs/basic_riscv64_tree/riscv64-unknown-elf/lib{{/|\\\\}}crt0.o"
+// C-RV64-BAREMETAL-LP64: "{{.*}}/Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1{{/|\\\\}}crtbegin.o"
+// C-RV64-BAREMETAL-LP64: "-L{{.*}}/Inputs/basic_riscv64_tree/riscv64-unknown-elf/lib"
+// C-RV64-BAREMETAL-LP64: "-L{{.*}}/Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1"
+// C-RV64-BAREMETAL-LP64: "--start-group" "-lc" "-lgloss" "--end-group" "-lgcc"
+// C-RV64-BAREMETAL-LP64: "{{.*}}/Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1{{/|\\\\}}crtend.o"
+
+// RUN: %clang %s -### -no-canonical-prefixes \
+// RUN:   -target riscv64-unknown-elf \
+// RUN:   --sysroot= \
+// RUN:   --gcc-toolchain=%S/Inputs/basic_riscv64_tree 2>&1 \
+// RUN:   | FileCheck -check-prefix=C-RV64-BAREMETAL-NOSYSROOT-LP64 %s
+
+// C-RV64-BAREMETAL-NOSYSROOT-LP64: "-fuse-init-array"
+// C-RV64-BAREMETAL-NOSYSROOT-LP64: "{{.*}}Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1/../../../../bin{{/|\\\\}}riscv64-unknown-elf-ld"
+// C-RV64-BAREMETAL-NOSYSROOT-LP64: "{{.*}}/Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1/../../../../riscv64-unknown-elf/lib{{/|\\\\}}crt0.o"
+// C-RV64-BAREMETAL-NOSYSROOT-LP64: "{{.*}}/Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1{{/|\\\\}}crtbegin.o"
+// C-RV64-BAREMETAL-NOSYSROOT-LP64: "-L{{.*}}/Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1/../../../../riscv64-unknown-elf{{/|\\\\}}lib"
+// C-RV64-BAREMETAL-NOSYSROOT-LP64: "-L{{.*}}/Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1"
+// C-RV64-BAREMETAL-NOSYSROOT-LP64: "--start-group" "-lc" "-lgloss" "--end-group" "-lgcc"
+// C-RV64-BAREMETAL-NOSYSROOT-LP64: "{{.*}}/Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1{{/|\\\\}}crtend.o"
+
+// RUN: %clangxx %s -### -no-canonical-prefixes \
+// RUN:   -target riscv64-unknown-elf -stdlib=libstdc++ \
+// RUN:   --gcc-toolchain=%S/Inputs/basic_riscv64_tree \
+// RUN:   --sysroot=%S/Inputs/basic_riscv64_tree/riscv64-unknown-elf 2>&1 \
+// RUN:   | FileCheck -check-prefix=CXX-RV64-BAREMETAL-LP64 %s
+
+// CXX-RV64-BAREMETAL-LP64: "-fuse-init-array"
+// CXX-RV64-BAREMETAL-LP64: "-internal-isystem" "{{.*}}Inputs/basic_riscv64_tree/riscv64-unknown-elf/include/c++{{/|\\\\}}8.0.1"
+// CXX-RV64-BAREMETAL-LP64: "{{.*}}Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1/../../../../bin{{/|\\\\}}riscv64-unknown-elf-ld"
+// CXX-RV64-BAREMETAL-LP64: "--sysroot={{.*}}/Inputs/basic_riscv64_tree/riscv64-unknown-elf"
+// CXX-RV64-BAREMETAL-LP64: "{{.*}}/Inputs/basic_riscv64_tree/riscv64-unknown-elf/lib{{/|\\\\}}crt0.o"
+// CXX-RV64-BAREMETAL-LP64: "{{.*}}/Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1{{/|\\\\}}crtbegin.o"
+// CXX-RV64-BAREMETAL-LP64: "-L{{.*}}/Inputs/basic_riscv64_tree/riscv64-unknown-elf/lib"
+// CXX-RV64-BAREMETAL-LP64: "-L{{.*}}/Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1"
+// CXX-RV64-BAREMETAL-LP64: "-lstdc++" "--start-group" "-lc" "-lgloss" "--end-group" "-lgcc"
+// CXX-RV64-BAREMETAL-LP64: "{{.*}}/Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1{{/|\\\\}}crtend.o"
+
+// RUN: %clangxx %s -### -no-canonical-prefixes \
+// RUN:   -target riscv64-unknown-elf -stdlib=libstdc++ \
+// RUN:   --sysroot= \
+// RUN:   --gcc-toolchain=%S/Inputs/basic_riscv64_tree 2>&1 \
+// RUN:   | FileCheck -check-prefix=CXX-RV64-BAREMETAL-NOSYSROOT-LP64 %s
+
+// CXX-RV64-BAREMETAL-NOSYSROOT-LP64: "-fuse-init-array"
+// CXX-RV64-BAREMETAL-NOSYSROOT-LP64: "-internal-isystem" "{{.*}}Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1/../../../../riscv64-unknown-elf/include/c++{{/|\\\\}}8.0.1"
+// CXX-RV64-BAREMETAL-NOSYSROOT-LP64: "{{.*}}Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1/../../../../bin{{/|\\\\}}riscv64-unknown-elf-ld"
+// CXX-RV64-BAREMETAL-NOSYSROOT-LP64: "{{.*}}/Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1/../../../../riscv64-unknown-elf/lib{{/|\\\\}}crt0.o"
+// CXX-RV64-BAREMETAL-NOSYSROOT-LP64: "{{.*}}/Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1{{/|\\\\}}crtbegin.o"
+// CXX-RV64-BAREMETAL-NOSYSROOT-LP64: "-L{{.*}}/Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1/../../../../riscv64-unknown-elf/lib"
+// CXX-RV64-BAREMETAL-NOSYSROOT-LP64: "-L{{.*}}/Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1"
+// CXX-RV64-BAREMETAL-NOSYSROOT-LP64: "-lstdc++" "--start-group" "-lc" "-lgloss" "--end-group" "-lgcc"
+// CXX-RV64-BAREMETAL-NOSYSROOT-LP64: "{{.*}}/Inputs/basic_riscv64_tree/lib/gcc/riscv64-unknown-elf/8.0.1{{/|\\\\}}crtend.o"
+
+// RUN: %clang %s -### -no-canonical-prefixes -fuse-ld=ld \
+// RUN:   -target riscv64-linux-unknown-elf \
+// RUN:   --gcc-toolchain=%S/Inputs/multilib_riscv_linux_sdk \
+// RUN:   --sysroot=%S/Inputs/multilib_riscv_linux_sdk/sysroot 2>&1 \
+// RUN:   | FileCheck -check-prefix=C-RV64-LINUX-MULTI-LP64 %s
+
+// C-RV64-LINUX-MULTI-LP64: "-fuse-init-array"
+// C-RV64-LINUX-MULTI-LP64: "{{.*}}/Inputs/multilib_riscv_linux_sdk/lib/gcc/riscv64-unknown-linux-gnu/7.2.0/../../../../riscv64-unknown-linux-gnu/bin{{/|\\\\}}ld"
+// C-RV64-LINUX-MULTI-LP64: "--sysroot={{.*}}/Inputs/multilib_riscv_linux_sdk/sysroot"
+// C-RV64-LINUX-MULTI-LP64: "-m" "elf64lriscv"
+// C-RV64-LINUX-MULTI-LP64: "-dynamic-linker" "/lib/ld-linux-riscv64-lp64.so.1"
+// C-RV64-LINUX-MULTI-LP64: "{{.*}}/Inputs/multilib_riscv_linux_sdk/lib/gcc/riscv64-unknown-linux-gnu/7.2.0/lib64/lp64{{/|\\\\}}crtbegin.o"
+// C-RV64-LINUX-MULTI-LP64: "-L{{.*}}/Inputs/multilib_riscv_linux_sdk/lib/gcc/riscv64-unknown-linux-gnu/7.2.0/lib64/lp64"
+// C-RV64-LINUX-MULTI-LP64: "-L{{.*}}/Inputs/multilib_riscv_linux_sdk/sysroot/lib64/lp64"
+// C-RV64-LINUX-MULTI-LP64: "-L{{.*}}/Inputs/multilib_riscv_linux_sdk/sysroot/usr/lib64/lp64"
+
+// RUN: %clang %s -### -no-canonical-prefixes -fuse-ld=ld \
+// RUN:   -target riscv64-linux-unknown-elf -march=rv64imafd -mabi=lp64d \
+// RUN:   --gcc-toolchain=%S/Inputs/multilib_riscv_linux_sdk \
+// RUN:   --sysroot=%S/Inputs/multilib_riscv_linux_sdk/sysroot 2>&1 \
+// RUN:   | FileCheck -check-prefix=C-RV64-LINUX-MULTI-LP64D %s
+
+// C-RV64-LINUX-MULTI-LP64D: "-fuse-init-array"
+// C-RV64-LINUX-MULTI-LP64D: "{{.*}}/Inputs/multilib_riscv_linux_sdk/lib/gcc/riscv64-unknown-linux-gnu/7.2.0/../../../../riscv64-unknown-linux-gnu/bin{{/|\\\\}}ld"
+// C-RV64-LINUX-MULTI-LP64D: "--sysroot={{.*}}/Inputs/multilib_riscv_linux_sdk/sysroot"
+// C-RV64-LINUX-MULTI-LP64D: "-m" "elf64lriscv"
+// C-RV64-LINUX-MULTI-LP64D: "-dynamic-linker" "/lib/ld-linux-riscv64-lp64d.so.1"
+// C-RV64-LINUX-MULTI-LP64D: "{{.*}}/Inputs/multilib_riscv_linux_sdk/lib/gcc/riscv64-unknown-linux-gnu/7.2.0/lib64/lp64d{{/|\\\\}}crtbegin.o"
+// C-RV64-LINUX-MULTI-LP64D: "-L{{.*}}/Inputs/multilib_riscv_linux_sdk/lib/gcc/riscv64-unknown-linux-gnu/7.2.0/lib64/lp64d"
+// C-RV64-LINUX-MULTI-LP64D: "-L{{.*}}/Inputs/multilib_riscv_linux_sdk/sysroot/lib64/lp64d"
+// C-RV64-LINUX-MULTI-LP64D: "-L{{.*}}/Inputs/multilib_riscv_linux_sdk/sysroot/usr/lib64/lp64d"
+
 // RUN: %clang -target riscv64 %s -emit-llvm -S -o - | FileCheck %s
 
 typedef __builtin_va_list va_list;