hack to replace arm version in triplet returned by config.guess
with the one we want for raspbian.
+diff --git a/llvm/cmake/config.guess.hack b/llvm/cmake/config.guess.hack
+new file mode 100644
+index 0000000000..13b18bf7b5
--- /dev/null
-+++ llvm-toolchain-9-9/llvm/cmake/config.guess.hack
++++ b/llvm/cmake/config.guess.hack
@@ -0,0 +1,2 @@
+#!/bin/bash -e
+$(dirname "$0")/config.guess | sed -r s/arm[a-zA-Z0-9]*/armv6/
---- llvm-toolchain-9-9.orig/llvm/cmake/modules/GetHostTriple.cmake
-+++ llvm-toolchain-9-9/llvm/cmake/modules/GetHostTriple.cmake
-@@ -20,3 +20,3 @@
+diff --git a/llvm/cmake/modules/GetHostTriple.cmake b/llvm/cmake/modules/GetHostTriple.cmake
+index 1be13bc01a..c9b870a2e2 100644
+--- a/llvm/cmake/modules/GetHostTriple.cmake
++++ b/llvm/cmake/modules/GetHostTriple.cmake
+@@ -45,7 +45,7 @@ function( get_host_triple var )
+ if(CMAKE_HOST_SYSTEM_NAME STREQUAL Windows AND NOT MSYS)
+ message(WARNING "unable to determine host target triple")
else()
- set(config_guess ${LLVM_MAIN_SRC_DIR}/cmake/config.guess)
+ set(config_guess ${LLVM_MAIN_SRC_DIR}/cmake/config.guess.hack)
execute_process(COMMAND sh ${config_guess}
---- llvm-toolchain-9-9.orig/compiler-rt/cmake/base-config-ix.cmake
-+++ llvm-toolchain-9-9/compiler-rt/cmake/base-config-ix.cmake
-@@ -205,4 +205,4 @@
+ RESULT_VARIABLE TT_RV
+ OUTPUT_VARIABLE TT_OUT
+diff --git a/compiler-rt/cmake/base-config-ix.cmake b/compiler-rt/cmake/base-config-ix.cmake
+index c6e95055b0..feef7b2eb8 100644
+--- a/compiler-rt/cmake/base-config-ix.cmake
++++ b/compiler-rt/cmake/base-config-ix.cmake
+@@ -248,10 +248,9 @@ macro(test_targets)
+ if(WIN32)
+ test_target_arch(arm "" "" "")
else()
-- test_target_arch(arm "" "-march=armv7-a" "-mfloat-abi=soft")
-- test_target_arch(armhf "" "-march=armv7-a" "-mfloat-abi=hard")
+- test_target_arch(armv4t "" "-march=armv4t" "-mfloat-abi=soft")
+ test_target_arch(arm "" "" "-mfloat-abi=soft")
+ test_target_arch(armhf "" "" "-mfloat-abi=hard")
test_target_arch(armv6m "" "-march=armv6m" "-mfloat-abi=soft")
+- test_target_arch(arm "" "-march=armv7-a" "-mfloat-abi=soft")
+- test_target_arch(armhf "" "-march=armv7-a" "-mfloat-abi=hard")
+ endif()
+ elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "avr")
+ test_target_arch(avr "__AVR__" "--target=avr")