diff --git a/debian/patches/fix-i386-path.diff b/debian/patches/fix-i386-path.diff
new file mode 100644
index 00000000..de78dba4
--- /dev/null
+++ b/debian/patches/fix-i386-path.diff
@@ -0,0 +1,80 @@
+Index: llvm-toolchain-snapshot_13~++20210404092006+c4c511337247/clang/lib/Driver/ToolChains/Gnu.cpp
+===================================================================
+--- llvm-toolchain-snapshot_13~++20210404092006+c4c511337247.orig/clang/lib/Driver/ToolChains/Gnu.cpp
++++ llvm-toolchain-snapshot_13~++20210404092006+c4c511337247/clang/lib/Driver/ToolChains/Gnu.cpp
+@@ -2983,9 +2983,13 @@ Generic_GCC::addGCCLibStdCxxIncludePaths
+           TripleStr, Multilib.includeSuffix(), DriverArgs, CC1Args))
+     return true;
+   // Detect Debian g++-multiarch-incdir.diff.
++  StringRef DebianMultiarch =
++      GCCInstallation.getTriple().getArch() == llvm::Triple::x86
++          ? "i386-linux-gnu"
++          : TripleStr;
+   if (addLibStdCXXIncludePaths(LibDir.str() + "/../include/c++/" + Version.Text,
+-                               TripleStr, Multilib.includeSuffix(), DriverArgs,
+-                               CC1Args, /*Debian=*/true))
++                               DebianMultiarch, Multilib.includeSuffix(),
++                               DriverArgs, CC1Args, /*Debian=*/true))
+     return true;
+ 
+   // Otherwise, fall back on a bunch of options which don't use multiarch
+Index: llvm-toolchain-snapshot_13~++20210404092006+c4c511337247/clang/test/Driver/linux-cross.cpp
+===================================================================
+--- llvm-toolchain-snapshot_13~++20210404092006+c4c511337247.orig/clang/test/Driver/linux-cross.cpp
++++ llvm-toolchain-snapshot_13~++20210404092006+c4c511337247/clang/test/Driver/linux-cross.cpp
+@@ -49,6 +49,55 @@
+ // DEBIAN_X86_64_M32-SAME: {{^}} "-L[[SYSROOT]]/lib"
+ // DEBIAN_X86_64_M32-SAME: {{^}} "-L[[SYSROOT]]/usr/lib"
+ 
++/// Test native GCC installation on Debian i386.
++// RUN: %clang -### %s --target=i686-linux-gnu --sysroot=%S/Inputs/debian_i386_tree \
++// RUN:   -resource-dir=%S/Inputs/resource_dir --stdlib=platform --rtlib=platform 2>&1 | FileCheck %s --check-prefix=DEBIAN_I686
++// DEBIAN_I686:      "-resource-dir" "[[RESOURCE:[^"]+]]"
++// DEBIAN_I686:      "-internal-isystem"
++// DEBIAN_I686-SAME: {{^}} "[[SYSROOT:[^"]+]]/usr/lib/gcc/i686-linux-gnu/10/../../../../include/c++/10"
++/// Debian specific - the path component after 'include' is i386-linux-gnu even
++/// though the installation is i686-linux-gnu.
++// DEBIAN_I686-SAME: {{^}} "-internal-isystem" "[[SYSROOT:[^"]+]]/usr/lib/gcc/i686-linux-gnu/10/../../../../include/i386-linux-gnu/c++/10"
++// DEBIAN_I686-SAME: {{^}} "-internal-isystem" "[[SYSROOT:[^"]+]]/usr/lib/gcc/i686-linux-gnu/10/../../../../include/c++/10/backward"
++// DEBIAN_I686-SAME: {{^}} "-internal-isystem" "[[RESOURCE]]/include"
++// DEBIAN_I686-SAME: {{^}} "-internal-isystem" "[[SYSROOT]]/usr/local/include"
++/// This resolves to /usr/i686-linux-gnu/include. Because it does not exist,
++/// having it does no harm albeit not ideal.
++// DEBIAN_I686-SAME: {{^}} "-internal-isystem" "[[SYSROOT:[^"]+]]/usr/lib/gcc/i686-linux-gnu/10/../../../../i686-linux-gnu/include"
++// DEBIAN_I686:      "-internal-externc-isystem"
++// DEBIAN_I686-SAME: {{^}} "[[SYSROOT]]/usr/include/i386-linux-gnu"
++// DEBIAN_I686:      "-L
++// DEBIAN_I686-SAME: {{^}}[[SYSROOT]]/usr/lib/gcc/i686-linux-gnu/10"
++// DEBIAN_I686-SAME: {{^}} "-L[[SYSROOT]]/lib/i386-linux-gnu"
++// DEBIAN_I686-SAME: {{^}} "-L[[SYSROOT]]/usr/lib/i386-linux-gnu"
++// DEBIAN_I686-SAME: {{^}} "-L[[SYSROOT]]/lib"
++// DEBIAN_I686-SAME: {{^}} "-L[[SYSROOT]]/usr/lib"
++
++/// Test -m64 on Debian i386.
++// RUN: %clang -### %s --target=i686-linux-gnu --sysroot=%S/Inputs/debian_i386_tree -m64 \
++// RUN:   -resource-dir=%S/Inputs/resource_dir --stdlib=platform --rtlib=platform 2>&1 | FileCheck %s --check-prefix=DEBIAN_I686_M64
++// DEBIAN_I686_M64:      "-resource-dir" "[[RESOURCE:[^"]+]]"
++// DEBIAN_I686_M64:      "-internal-isystem"
++// DEBIAN_I686_M64-SAME: {{^}} "[[SYSROOT:[^"]+]]/usr/lib/gcc/i686-linux-gnu/10/../../../../include/c++/10"
++/// Debian specific - the path component after 'include' is i386-linux-gnu even
++/// though the installation is i686-linux-gnu.
++// DEBIAN_I686_M64-SAME: {{^}} "-internal-isystem" "[[SYSROOT:[^"]+]]/usr/lib/gcc/i686-linux-gnu/10/../../../../include/i386-linux-gnu/c++/10/64"
++// DEBIAN_I686_M64-SAME: {{^}} "-internal-isystem" "[[SYSROOT:[^"]+]]/usr/lib/gcc/i686-linux-gnu/10/../../../../include/c++/10/backward"
++// DEBIAN_I686_M64-SAME: {{^}} "-internal-isystem" "[[RESOURCE]]/include"
++// DEBIAN_I686_M64-SAME: {{^}} "-internal-isystem" "[[SYSROOT]]/usr/local/include"
++// DEBIAN_I686_M64-SAME: {{^}} "-internal-isystem" "[[SYSROOT:[^"]+]]/usr/lib/gcc/i686-linux-gnu/10/../../../../i686-linux-gnu/include"
++// DEBIAN_I686_M64:      "-internal-externc-isystem"
++// DEBIAN_I686_M64-SAME: {{^}} "[[SYSROOT]]/usr/include/x86_64-linux-gnu"
++// DEBIAN_I686_M64:      "-L
++// DEBIAN_I686_M64-SAME: {{^}}[[SYSROOT]]/usr/lib/gcc/i686-linux-gnu/10/64"
++// DEBIAN_I686_M64-SAME: {{^}} "-L[[SYSROOT]]/usr/lib/gcc/i686-linux-gnu/10/../../../../lib64"
++// DEBIAN_I686_M64-SAME: {{^}} "-L[[SYSROOT]]/lib/x86_64-linux-gnu"
++// DEBIAN_I686_M64-SAME: {{^}} "-L[[SYSROOT]]/lib/../lib64"
++// DEBIAN_I686_M64-SAME: {{^}} "-L[[SYSROOT]]/usr/lib/x86_64-linux-gnu"
++// DEBIAN_I686_M64-SAME: {{^}} "-L[[SYSROOT]]/usr/lib/../lib64"
++// DEBIAN_I686_M64-SAME: {{^}} "-L[[SYSROOT]]/lib"
++// DEBIAN_I686_M64-SAME: {{^}} "-L[[SYSROOT]]/usr/lib"
++
+ /// Test a cross compiler.
+ // RUN: %clang -### %s --target=aarch64-linux-gnu --sysroot=%S/Inputs/debian_multiarch_tree \
+ // RUN:   -resource-dir=%S/Inputs/resource_dir --stdlib=platform --rtlib=platform 2>&1 | FileCheck %s --check-prefix=DEBIAN_AARCH64