Index: clang/lib/Driver/ToolChains/RISCVToolchain.cpp
===================================================================
--- clang/lib/Driver/ToolChains/RISCVToolchain.cpp
+++ clang/lib/Driver/ToolChains/RISCVToolchain.cpp
@@ -33,6 +33,8 @@
     getFilePaths().push_back(GCCInstallation.getInstallPath().str());
     getProgramPaths().push_back(
         (GCCInstallation.getParentLibPath() + "/../bin").str());
+  } else {
+    getProgramPaths().push_back(D.Dir);
   }
 }
 
@@ -74,17 +76,22 @@
   if (!getDriver().SysRoot.empty())
     return getDriver().SysRoot;
 
-  if (!GCCInstallation.isValid())
-    return std::string();
-
-  StringRef LibDir = GCCInstallation.getParentLibPath();
-  StringRef TripleStr = GCCInstallation.getTriple().str();
-  std::string SysRootDir = LibDir.str() + "/../" + TripleStr.str();
+  SmallString<128> SysRootDir;
+  if (GCCInstallation.isValid()) {
+    StringRef LibDir = GCCInstallation.getParentLibPath();
+    StringRef TripleStr = GCCInstallation.getTriple().str();
+    llvm::sys::path::append(SysRootDir, LibDir, "..", TripleStr);
+  } else {
+    // Use the triple as provided to the driver. Unlike the parsed triple
+    // this has not been normalized to always contain every field.
+    llvm::sys::path::append(SysRootDir, getDriver().Dir, "..",
+                            getDriver().getTargetTriple());
+  }
 
   if (!llvm::sys::fs::exists(SysRootDir))
     return std::string();
 
-  return SysRootDir;
+  return SysRootDir.str();
 }
 
 void RISCV::Linker::ConstructJob(Compilation &C, const JobAction &JA,
Index: clang/test/Driver/Inputs/basic_riscv32_nogcc_tree/bin/riscv32-unknown-elf-ld
===================================================================
--- /dev/null
+++ clang/test/Driver/Inputs/basic_riscv32_nogcc_tree/bin/riscv32-unknown-elf-ld
@@ -0,0 +1 @@
+#!/bin/true
Index: clang/test/Driver/Inputs/basic_riscv64_nogcc_tree/bin/riscv64-unknown-elf-ld
===================================================================
--- /dev/null
+++ clang/test/Driver/Inputs/basic_riscv64_nogcc_tree/bin/riscv64-unknown-elf-ld
@@ -0,0 +1 @@
+#!/bin/true
Index: clang/test/Driver/riscv32-toolchain-extra.c
===================================================================
--- /dev/null
+++ clang/test/Driver/riscv32-toolchain-extra.c
@@ -0,0 +1,33 @@
+// A basic clang -cc1 command-line, and simple environment check.
+
+// The tests here are similar to those in riscv32-toolchain.c, however
+// these tests need to create symlinks to test directory trees in order to
+// set up the environment and therefore shell support is required.
+// REQUIRES: shell
+// UNSUPPORTED: system-windows
+
+// If there is no GCC install detected then the driver searches for executables
+// and runtime starting from the directory tree above the driver itself.
+// The test below checks that the driver correctly finds the linker and
+// runtime if and only if they exist.
+//
+// RUN: mkdir -p %T/testroot-riscv32-baremetal-nogcc/bin
+// RUN: [ ! -s %T/testroot-riscv32-baremetal-nogcc/bin/clang ] || rm %T/testroot-riscv32-baremetal-nogcc/bin/clang
+// RUN: [ ! -s %T/testroot-riscv32-baremetal-nogcc/bin/riscv32-unknown-elf-ld ] || rm %T/testroot-riscv32-baremetal-nogcc/bin/riscv32-unknown-elf-ld
+// RUN: [ ! -s %T/testroot-riscv32-baremetal-nogcc/riscv32-unknown-elf ] || rm %T/testroot-riscv32-baremetal-nogcc/riscv32-unknown-elf
+// RUN: ln -s %clang %T/testroot-riscv32-baremetal-nogcc/bin/clang
+// RUN: ln -s %S/Inputs/basic_riscv32_nogcc_tree/bin/riscv32-unknown-elf-ld %T/testroot-riscv32-baremetal-nogcc/bin/riscv32-unknown-elf-ld
+// RUN: ln -s %S/Inputs/basic_riscv32_nogcc_tree/riscv32-unknown-elf %T/testroot-riscv32-baremetal-nogcc/riscv32-unknown-elf
+// RUN: %T/testroot-riscv32-baremetal-nogcc/bin/clang %s -### -no-canonical-prefixes \
+// RUN:    -target riscv32-unknown-elf 2>&1 \
+// RUN:    | FileCheck -check-prefix=C-RV32-BAREMETAL-ILP32-NOGCC %s
+
+// C-RV32-BAREMETAL-ILP32-NOGCC: InstalledDir: [[DRIVERDIR:.*]]
+// C-RV32-BAREMETAL-ILP32-NOGCC: "-fuse-init-array"
+// C-RV32-BAREMETAL-ILP32-NOGCC: "-internal-isystem" "[[DRIVERDIR]]/../riscv32-unknown-elf/include"
+// C-RV32-BAREMETAL-ILP32-NOGCC: "[[DRIVERDIR]]/riscv32-unknown-elf-ld"
+// C-RV32-BAREMETAL-ILP32-NOGCC: "[[DRIVERDIR]]/../riscv32-unknown-elf/lib/crt0.o"
+// C-RV32-BAREMETAL-ILP32-NOGCC: "[[DRIVERDIR]]/../riscv32-unknown-elf/lib/crtbegin.o"
+// C-RV32-BAREMETAL-ILP32-NOGCC: "-L[[DRIVERDIR]]/../riscv32-unknown-elf/lib"
+// C-RV32-BAREMETAL-ILP32-NOGCC: "--start-group" "-lc" "-lgloss" "--end-group" "-lgcc"
+// C-RV32-BAREMETAL-ILP32-NOGCC: "[[DRIVERDIR]]/../riscv32-unknown-elf/lib/crtend.o"
Index: clang/test/Driver/riscv64-toolchain-extra.c
===================================================================
--- /dev/null
+++ clang/test/Driver/riscv64-toolchain-extra.c
@@ -0,0 +1,33 @@
+// A basic clang -cc1 command-line, and simple environment check.
+
+// The tests here are similar to those in riscv64-toolchain.c, however
+// these tests need to create symlinks to test directory trees in order to
+// set up the environment and therefore shell support is required.
+// REQUIRES: shell
+// UNSUPPORTED: system-windows
+
+// If there is no GCC install detected then the driver searches for executables
+// and runtime starting from the directory tree above the driver itself.
+// The test below checks that the driver correctly finds the linker and
+// runtime if and only if they exist.
+//
+// RUN: mkdir -p %T/testroot-riscv64-baremetal-nogcc/bin
+// RUN: [ ! -s %T/testroot-riscv64-baremetal-nogcc/bin/clang ] || rm %T/testroot-riscv64-baremetal-nogcc/bin/clang
+// RUN: [ ! -s %T/testroot-riscv64-baremetal-nogcc/bin/riscv64-unknown-elf-ld ] || rm %T/testroot-riscv64-baremetal-nogcc/bin/riscv64-unknown-elf-ld
+// RUN: [ ! -s %T/testroot-riscv64-baremetal-nogcc/riscv64-unknown-elf ] || rm %T/testroot-riscv64-baremetal-nogcc/riscv64-unknown-elf
+// RUN: ln -s %clang %T/testroot-riscv64-baremetal-nogcc/bin/clang
+// RUN: ln -s %S/Inputs/basic_riscv64_nogcc_tree/bin/riscv64-unknown-elf-ld %T/testroot-riscv64-baremetal-nogcc/bin/riscv64-unknown-elf-ld
+// RUN: ln -s %S/Inputs/basic_riscv64_nogcc_tree/riscv64-unknown-elf %T/testroot-riscv64-baremetal-nogcc/riscv64-unknown-elf
+// RUN: %T/testroot-riscv64-baremetal-nogcc/bin/clang %s -### -no-canonical-prefixes \
+// RUN:    -target riscv64-unknown-elf 2>&1 \
+// RUN:    | FileCheck -check-prefix=C-RV64-BAREMETAL-LP64-NOGCC %s
+
+// C-RV64-BAREMETAL-LP64-NOGCC: InstalledDir: [[DRIVERDIR:.*]]
+// C-RV64-BAREMETAL-LP64-NOGCC: "-fuse-init-array"
+// C-RV64-BAREMETAL-LP64-NOGCC: "-internal-isystem" "[[DRIVERDIR]]/../riscv64-unknown-elf/include"
+// C-RV64-BAREMETAL-LP64-NOGCC: "[[DRIVERDIR]]/riscv64-unknown-elf-ld"
+// C-RV64-BAREMETAL-LP64-NOGCC: "[[DRIVERDIR]]/../riscv64-unknown-elf/lib/crt0.o"
+// C-RV64-BAREMETAL-LP64-NOGCC: "[[DRIVERDIR]]/../riscv64-unknown-elf/lib/crtbegin.o"
+// C-RV64-BAREMETAL-LP64-NOGCC: "-L[[DRIVERDIR]]/../riscv64-unknown-elf/lib"
+// C-RV64-BAREMETAL-LP64-NOGCC: "--start-group" "-lc" "-lgloss" "--end-group" "-lgcc"
+// C-RV64-BAREMETAL-LP64-NOGCC: "[[DRIVERDIR]]/../riscv64-unknown-elf/lib/crtend.o"