diff --git a/compiler-rt/lib/ubsan/CMakeLists.txt b/compiler-rt/lib/ubsan/CMakeLists.txt
index 5d45a53d02dbd..a6c98c40ec772 100644
--- a/compiler-rt/lib/ubsan/CMakeLists.txt
+++ b/compiler-rt/lib/ubsan/CMakeLists.txt
@@ -43,18 +43,15 @@ include_directories(..)
 set(UBSAN_CFLAGS ${SANITIZER_COMMON_CFLAGS})
 append_list_if(MSVC /Zl UBSAN_CFLAGS)
 append_rtti_flag(OFF UBSAN_CFLAGS)
-append_list_if(SANITIZER_CAN_USE_CXXABI -DUBSAN_CAN_USE_CXXABI UBSAN_CFLAGS)
 
 # Too many existing bugs, needs cleanup.
 append_list_if(COMPILER_RT_HAS_WNO_FORMAT -Wno-format UBSAN_CFLAGS)
 
 set(UBSAN_STANDALONE_CFLAGS ${SANITIZER_COMMON_CFLAGS})
 append_rtti_flag(OFF UBSAN_STANDALONE_CFLAGS)
-append_list_if(SANITIZER_CAN_USE_CXXABI -DUBSAN_CAN_USE_CXXABI UBSAN_STANDALONE_CFLAGS)
 
 set(UBSAN_CXXFLAGS ${SANITIZER_COMMON_CFLAGS})
 append_rtti_flag(ON UBSAN_CXXFLAGS)
-append_list_if(SANITIZER_CAN_USE_CXXABI -DUBSAN_CAN_USE_CXXABI UBSAN_CXXFLAGS)
 
 # Silence warnings in system headers with MSVC.
 if(NOT CLANG_CL)
diff --git a/compiler-rt/lib/ubsan/ubsan_handlers.cpp b/compiler-rt/lib/ubsan/ubsan_handlers.cpp
index ac7001c74afb5..ee9e3ccd0b1f6 100644
--- a/compiler-rt/lib/ubsan/ubsan_handlers.cpp
+++ b/compiler-rt/lib/ubsan/ubsan_handlers.cpp
@@ -899,10 +899,7 @@ static void handleCFIBadIcall(CFICheckFailData *Data, ValueHandle Function,
 
 namespace __ubsan {
 
-#ifdef UBSAN_CAN_USE_CXXABI
-
 #ifdef _WIN32
-
 extern "C" void __ubsan_handle_cfi_bad_type_default(CFICheckFailData *Data,
                                                     ValueHandle Vtable,
                                                     bool ValidVtable,
@@ -911,18 +908,12 @@ extern "C" void __ubsan_handle_cfi_bad_type_default(CFICheckFailData *Data,
 }
 
 WIN_WEAK_ALIAS(__ubsan_handle_cfi_bad_type, __ubsan_handle_cfi_bad_type_default)
-#else
-SANITIZER_WEAK_ATTRIBUTE
 #endif
-void __ubsan_handle_cfi_bad_type(CFICheckFailData *Data, ValueHandle Vtable,
-                                 bool ValidVtable, ReportOptions Opts);
-
-#else
+SANITIZER_WEAK_ATTRIBUTE
 void __ubsan_handle_cfi_bad_type(CFICheckFailData *Data, ValueHandle Vtable,
                                  bool ValidVtable, ReportOptions Opts) {
   Die();
 }
-#endif
 
 }  // namespace __ubsan
 
diff --git a/llvm/utils/gn/secondary/compiler-rt/lib/lsan/BUILD.gn b/llvm/utils/gn/secondary/compiler-rt/lib/lsan/BUILD.gn
index 77b251030c671..2ac06c4e6c75f 100644
--- a/llvm/utils/gn/secondary/compiler-rt/lib/lsan/BUILD.gn
+++ b/llvm/utils/gn/secondary/compiler-rt/lib/lsan/BUILD.gn
@@ -1,7 +1,6 @@
 source_set("common_sources") {
   configs -= [ "//llvm/utils/gn/build:llvm_code" ]
   configs += [ "//llvm/utils/gn/build:crt_code" ]
-  defines = [ "UBSAN_CAN_USE_CXXABI" ]
   deps = [
     "//compiler-rt/lib/interception:sources",
     "//compiler-rt/lib/sanitizer_common:sources",
@@ -18,7 +17,6 @@ source_set("common_sources") {
 source_set("sources") {
   configs -= [ "//llvm/utils/gn/build:llvm_code" ]
   configs += [ "//llvm/utils/gn/build:crt_code" ]
-  defines = [ "UBSAN_CAN_USE_CXXABI" ]
   deps = [
     "//compiler-rt/lib/interception:sources",
     "//compiler-rt/lib/sanitizer_common:sources",
diff --git a/llvm/utils/gn/secondary/compiler-rt/lib/ubsan/BUILD.gn b/llvm/utils/gn/secondary/compiler-rt/lib/ubsan/BUILD.gn
index d3b4a406f8b50..c331193ca94c9 100644
--- a/llvm/utils/gn/secondary/compiler-rt/lib/ubsan/BUILD.gn
+++ b/llvm/utils/gn/secondary/compiler-rt/lib/ubsan/BUILD.gn
@@ -27,7 +27,6 @@ gen_version_script("version_script") {
 source_set("sources") {
   configs -= [ "//llvm/utils/gn/build:llvm_code" ]
   configs += [ "//llvm/utils/gn/build:crt_code" ]
-  defines = [ "UBSAN_CAN_USE_CXXABI" ]
   deps = [
     "//compiler-rt/lib/interception:sources",
     "//compiler-rt/lib/sanitizer_common:sources",
@@ -65,7 +64,6 @@ source_set("standalone_sources") {
   configs -= [ "//llvm/utils/gn/build:llvm_code" ]
   configs -= [ "//llvm/utils/gn/build:no_rtti" ]
   configs += [ "//llvm/utils/gn/build:crt_code" ]
-  defines = [ "UBSAN_CAN_USE_CXXABI" ]
   sources = [
     "ubsan_diag_standalone.cpp",
     "ubsan_init_standalone.cpp",
@@ -77,7 +75,6 @@ source_set("cxx_sources") {
   configs -= [ "//llvm/utils/gn/build:llvm_code" ]
   configs -= [ "//llvm/utils/gn/build:no_rtti" ]
   configs += [ "//llvm/utils/gn/build:crt_code" ]
-  defines = [ "UBSAN_CAN_USE_CXXABI" ]
   sources = [
     "ubsan_handlers_cxx.cpp",
     "ubsan_handlers_cxx.h",