diff --git a/clang/lib/Driver/ToolChains/FreeBSD.cpp b/clang/lib/Driver/ToolChains/FreeBSD.cpp
--- a/clang/lib/Driver/ToolChains/FreeBSD.cpp
+++ b/clang/lib/Driver/ToolChains/FreeBSD.cpp
@@ -389,10 +389,10 @@
   // back to '/usr/lib' if it doesn't exist.
   if ((Triple.getArch() == llvm::Triple::x86 || Triple.isMIPS32() ||
        Triple.isPPC32()) &&
-      D.getVFS().exists(getDriver().SysRoot + "/usr/lib32/crt1.o"))
-    getFilePaths().push_back(getDriver().SysRoot + "/usr/lib32");
+      D.getVFS().exists(concat(getDriver().SysRoot, "/usr/lib32/crt1.o")))
+    getFilePaths().push_back(concat(getDriver().SysRoot, "/usr/lib32"));
   else
-    getFilePaths().push_back(getDriver().SysRoot + "/usr/lib");
+    getFilePaths().push_back(concat(getDriver().SysRoot, "/usr/lib"));
 }
 
 ToolChain::CXXStdlibType FreeBSD::GetDefaultCXXStdlibType() const {
@@ -411,14 +411,14 @@
 void FreeBSD::addLibCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
                                     llvm::opt::ArgStringList &CC1Args) const {
   addSystemInclude(DriverArgs, CC1Args,
-                   getDriver().SysRoot + "/usr/include/c++/v1");
+                   concat(getDriver().SysRoot, "/usr/include/c++/v1"));
 }
 
 void FreeBSD::addLibStdCxxIncludePaths(
     const llvm::opt::ArgList &DriverArgs,
     llvm::opt::ArgStringList &CC1Args) const {
-  addLibStdCXXIncludePaths(getDriver().SysRoot + "/usr/include/c++/4.2", "", "",
-                           DriverArgs, CC1Args);
+  addLibStdCXXIncludePaths(concat(getDriver().SysRoot, "/usr/include/c++/4.2"),
+                           "", "", DriverArgs, CC1Args);
 }
 
 void FreeBSD::AddCXXStdlibLibArgs(const ArgList &Args,
diff --git a/clang/lib/Driver/ToolChains/OpenBSD.cpp b/clang/lib/Driver/ToolChains/OpenBSD.cpp
--- a/clang/lib/Driver/ToolChains/OpenBSD.cpp
+++ b/clang/lib/Driver/ToolChains/OpenBSD.cpp
@@ -284,7 +284,7 @@
 OpenBSD::OpenBSD(const Driver &D, const llvm::Triple &Triple,
                  const ArgList &Args)
     : Generic_ELF(D, Triple, Args) {
-  getFilePaths().push_back(getDriver().SysRoot + "/usr/lib");
+  getFilePaths().push_back(concat(getDriver().SysRoot, "/usr/lib"));
 }
 
 void OpenBSD::AddClangSystemIncludeArgs(
@@ -317,13 +317,14 @@
     return;
   }
 
-  addExternCSystemInclude(DriverArgs, CC1Args, D.SysRoot + "/usr/include");
+  addExternCSystemInclude(DriverArgs, CC1Args,
+                          concat(D.SysRoot, "/usr/include"));
 }
 
 void OpenBSD::addLibCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
                                     llvm::opt::ArgStringList &CC1Args) const {
   addSystemInclude(DriverArgs, CC1Args,
-                   getDriver().SysRoot + "/usr/include/c++/v1");
+                   concat(getDriver().SysRoot, "/usr/include/c++/v1"));
 }
 
 void OpenBSD::AddCXXStdlibLibArgs(const ArgList &Args,
diff --git a/clang/test/Driver/Inputs/basic_freebsd_libcxx_tree/usr/bin/.keep b/clang/test/Driver/Inputs/basic_freebsd_libcxx_tree/usr/bin/.keep
new file mode 100644
diff --git a/clang/test/Driver/Inputs/basic_freebsd_libcxx_tree/usr/include/c++/v1/.keep b/clang/test/Driver/Inputs/basic_freebsd_libcxx_tree/usr/include/c++/v1/.keep
new file mode 100644
diff --git a/clang/test/Driver/Inputs/basic_freebsd_libcxx_tree/usr/lib/.keep b/clang/test/Driver/Inputs/basic_freebsd_libcxx_tree/usr/lib/.keep
new file mode 100644
diff --git a/clang/test/Driver/Inputs/basic_openbsd_libcxx_tree/usr/bin/.keep b/clang/test/Driver/Inputs/basic_openbsd_libcxx_tree/usr/bin/.keep
new file mode 100644
diff --git a/clang/test/Driver/Inputs/basic_openbsd_libcxx_tree/usr/include/c++/v1/.keep b/clang/test/Driver/Inputs/basic_openbsd_libcxx_tree/usr/include/c++/v1/.keep
new file mode 100644
diff --git a/clang/test/Driver/Inputs/basic_openbsd_libcxx_tree/usr/lib/.keep b/clang/test/Driver/Inputs/basic_openbsd_libcxx_tree/usr/lib/.keep
new file mode 100644
diff --git a/clang/test/Driver/freebsd.cpp b/clang/test/Driver/freebsd.cpp
--- a/clang/test/Driver/freebsd.cpp
+++ b/clang/test/Driver/freebsd.cpp
@@ -20,3 +20,23 @@
 // CHECK-PG-FOURTEEN: "-lc++" "-lm"
 // CHECK-PG-TEN: "-lc++_p" "-lm_p"
 // CHECK-PG-NINE: "-lstdc++_p" "-lm_p"
+
+// Test include paths with a sysroot.
+// RUN: %clangxx %s -### -fsyntax-only 2>&1 \
+// RUN:     --target=amd64-unknown-freebsd \
+// RUN:     --sysroot=%S/Inputs/basic_openbsd_libcxx_tree \
+// RUN:     -resource-dir=%S/Inputs/resource_dir \
+// RUN:   | FileCheck --check-prefix=CHECK-LIBCXX-SYSROOT %s
+// CHECK-LIBCXX-SYSROOT: "-cc1"
+// CHECK-LIBCXX-SYSROOT-SAME: "-isysroot" "[[SYSROOT:[^"]+]]"
+// CHECK-LIBCXX-SYSROOT-SAME: "-internal-isystem" "[[SYSROOT]]/usr/include/c++/v1"
+
+// Test include paths when the sysroot path ends with `/`.
+// RUN: %clangxx %s -### -fsyntax-only 2>&1 \
+// RUN:     --target=amd64-unknown-freebsd \
+// RUN:     --sysroot=%S/Inputs/basic_openbsd_libcxx_tree/ \
+// RUN:     -resource-dir=%S/Inputs/resource_dir \
+// RUN:   | FileCheck --check-prefix=CHECK-LIBCXX-SYSROOT-SLASH %s
+// CHECK-LIBCXX-SYSROOT-SLASH: "-cc1"
+// CHECK-LIBCXX-SYSROOT-SLASH-SAME: "-isysroot" "[[SYSROOT:[^"]+/]]"
+// CHECK-LIBCXX-SYSROOT-SLASH-SAME: "-internal-isystem" "[[SYSROOT]]usr/include/c++/v1"
diff --git a/clang/test/Driver/openbsd.cpp b/clang/test/Driver/openbsd.cpp
--- a/clang/test/Driver/openbsd.cpp
+++ b/clang/test/Driver/openbsd.cpp
@@ -19,3 +19,23 @@
 // RUN: %clangxx %s -### -pg -o %t.o -target arm-unknown-openbsd 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-PG-CXX %s
 // CHECK-PG-CXX: "-lc++_p" "-lc++abi_p" "-lpthread_p" "-lm_p"
+
+// Test include paths with a sysroot.
+// RUN: %clangxx %s -### -fsyntax-only 2>&1 \
+// RUN:     --target=amd64-pc-openbsd \
+// RUN:     --sysroot=%S/Inputs/basic_openbsd_libcxx_tree \
+// RUN:     -resource-dir=%S/Inputs/resource_dir \
+// RUN:   | FileCheck --check-prefix=CHECK-LIBCXX-SYSROOT %s
+// CHECK-LIBCXX-SYSROOT: "-cc1"
+// CHECK-LIBCXX-SYSROOT-SAME: "-isysroot" "[[SYSROOT:[^"]+]]"
+// CHECK-LIBCXX-SYSROOT-SAME: "-internal-isystem" "[[SYSROOT]]/usr/include/c++/v1"
+
+// Test include paths when the sysroot path ends with `/`.
+// RUN: %clangxx %s -### -fsyntax-only 2>&1 \
+// RUN:     --target=amd64-pc-openbsd \
+// RUN:     --sysroot=%S/Inputs/basic_openbsd_libcxx_tree/ \
+// RUN:     -resource-dir=%S/Inputs/resource_dir \
+// RUN:   | FileCheck --check-prefix=CHECK-LIBCXX-SYSROOT-SLASH %s
+// CHECK-LIBCXX-SYSROOT-SLASH: "-cc1"
+// CHECK-LIBCXX-SYSROOT-SLASH-SAME: "-isysroot" "[[SYSROOT:[^"]+/]]"
+// CHECK-LIBCXX-SYSROOT-SLASH-SAME: "-internal-isystem" "[[SYSROOT]]usr/include/c++/v1"