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/llvm/clang/test/Driver/freebsd-header-search.cpp b/llvm/clang/test/Driver/freebsd-header-search.cpp
new file mode 100644
--- /dev/null
+++ b/llvm/clang/test/Driver/freebsd-header-search.cpp
@@ -0,0 +1,12 @@
+// Test include paths when the sysroot path ends with `/`.
+// RUN: %clang -### %s -fsyntax-only 2>&1 \
+// RUN:     --target=amd64-unknown-freebsd \
+// RUN:     -stdlib=libc++ \
+// RUN:     -ccc-install-dir %S/Inputs/basic_freebsd_tree/usr/bin \
+// RUN:     -resource-dir=%S/Inputs/resource_dir \
+// RUN:     --sysroot=%S/Inputs/basic_linux_libcxx_tree/ \
+// RUN:     --gcc-toolchain="" \
+// RUN:   | FileCheck --check-prefix=CHECK-BASIC-LIBCXX-SYSROOT-SLASH %s
+// CHECK-BASIC-LIBCXX-SYSROOT-SLASH: "-cc1"
+// CHECK-BASIC-LIBCXX-SYSROOT-SLASH-SAME: "-isysroot" "[[SYSROOT:[^"]+/]]"
+// CHECK-BASIC-LIBCXX-SYSROOT-SLASH-SAME: "-internal-isystem" "[[SYSROOT]]usr/include/c++/v1"