diff --git a/compiler-rt/cmake/Modules/AddCompilerRT.cmake b/compiler-rt/cmake/Modules/AddCompilerRT.cmake
--- a/compiler-rt/cmake/Modules/AddCompilerRT.cmake
+++ b/compiler-rt/cmake/Modules/AddCompilerRT.cmake
@@ -381,6 +381,8 @@
     endif()
     set_target_properties(${libname} PROPERTIES
         OUTPUT_NAME ${output_name_${libname}})
+    set_target_properties(${libname} PROPERTIES
+        C_STANDARD 11)
     set_target_properties(${libname} PROPERTIES FOLDER "Compiler-RT Runtime")
     if(LIB_LINK_LIBS)
       target_link_libraries(${libname} PRIVATE ${LIB_LINK_LIBS})
diff --git a/compiler-rt/cmake/builtin-config-ix.cmake b/compiler-rt/cmake/builtin-config-ix.cmake
--- a/compiler-rt/cmake/builtin-config-ix.cmake
+++ b/compiler-rt/cmake/builtin-config-ix.cmake
@@ -8,7 +8,6 @@
 builtin_check_c_compiler_flag(-fPIC                 COMPILER_RT_HAS_FPIC_FLAG)
 builtin_check_c_compiler_flag(-fPIE                 COMPILER_RT_HAS_FPIE_FLAG)
 builtin_check_c_compiler_flag(-fno-builtin          COMPILER_RT_HAS_FNO_BUILTIN_FLAG)
-builtin_check_c_compiler_flag(-std=c11              COMPILER_RT_HAS_STD_C11_FLAG)
 builtin_check_c_compiler_flag(-fvisibility=hidden   COMPILER_RT_HAS_VISIBILITY_HIDDEN_FLAG)
 builtin_check_c_compiler_flag(-fomit-frame-pointer  COMPILER_RT_HAS_OMIT_FRAME_POINTER_FLAG)
 builtin_check_c_compiler_flag(-ffreestanding        COMPILER_RT_HAS_FFREESTANDING_FLAG)
diff --git a/compiler-rt/cmake/config-ix.cmake b/compiler-rt/cmake/config-ix.cmake
--- a/compiler-rt/cmake/config-ix.cmake
+++ b/compiler-rt/cmake/config-ix.cmake
@@ -57,7 +57,6 @@
 # CodeGen options.
 check_c_compiler_flag(-ffreestanding         COMPILER_RT_HAS_FFREESTANDING_FLAG)
 check_c_compiler_flag(-fomit-frame-pointer   COMPILER_RT_HAS_OMIT_FRAME_POINTER_FLAG)
-check_c_compiler_flag(-std=c11               COMPILER_RT_HAS_STD_C11_FLAG)
 check_c_compiler_flag(-fcf-protection=full   COMPILER_RT_HAS_FCF_PROTECTION_FLAG)
 check_cxx_compiler_flag(-fPIC                COMPILER_RT_HAS_FPIC_FLAG)
 check_cxx_compiler_flag(-fPIE                COMPILER_RT_HAS_FPIE_FLAG)
diff --git a/compiler-rt/cmake/crt-config-ix.cmake b/compiler-rt/cmake/crt-config-ix.cmake
--- a/compiler-rt/cmake/crt-config-ix.cmake
+++ b/compiler-rt/cmake/crt-config-ix.cmake
@@ -5,7 +5,6 @@
 set(TEST_COMPILE_ONLY On)
 
 builtin_check_c_compiler_flag(-fPIC                 COMPILER_RT_HAS_FPIC_FLAG)
-builtin_check_c_compiler_flag(-std=c11              COMPILER_RT_HAS_STD_C11_FLAG)
 builtin_check_c_compiler_flag(-Wno-pedantic         COMPILER_RT_HAS_WNO_PEDANTIC)
 builtin_check_c_compiler_flag(-fno-lto              COMPILER_RT_HAS_FNO_LTO_FLAG)
 builtin_check_c_compiler_flag(-fno-profile-generate COMPILER_RT_HAS_FNO_PROFILE_GENERATE_FLAG)
diff --git a/compiler-rt/lib/builtins/CMakeLists.txt b/compiler-rt/lib/builtins/CMakeLists.txt
--- a/compiler-rt/lib/builtins/CMakeLists.txt
+++ b/compiler-rt/lib/builtins/CMakeLists.txt
@@ -684,8 +684,6 @@
 
   append_list_if(COMPILER_RT_HAS_FLOAT16 -DCOMPILER_RT_HAS_FLOAT16 BUILTIN_CFLAGS)
 
-  append_list_if(COMPILER_RT_HAS_STD_C11_FLAG -std=c11 BUILTIN_CFLAGS)
-
   # These flags would normally be added to CMAKE_C_FLAGS by the llvm
   # cmake step. Add them manually if this is a standalone build.
   if(COMPILER_RT_STANDALONE_BUILD)
diff --git a/compiler-rt/lib/crt/CMakeLists.txt b/compiler-rt/lib/crt/CMakeLists.txt
--- a/compiler-rt/lib/crt/CMakeLists.txt
+++ b/compiler-rt/lib/crt/CMakeLists.txt
@@ -37,7 +37,6 @@
   check_section_exists(".init_array" COMPILER_RT_HAS_INITFINI_ARRAY
     SOURCE "volatile int x;\n__attribute__((constructor)) void f(void) {x = 0;}\nint main(void) { return 0; }\n")
 
-  append_list_if(COMPILER_RT_HAS_STD_C11_FLAG -std=c11 CRT_CFLAGS)
   append_list_if(COMPILER_RT_HAS_INITFINI_ARRAY -DCRT_HAS_INITFINI_ARRAY CRT_CFLAGS)
   append_list_if(COMPILER_RT_CRT_USE_EH_FRAME_REGISTRY -DEH_USE_FRAME_REGISTRY CRT_CFLAGS)
   append_list_if(COMPILER_RT_HAS_FPIC_FLAG -fPIC CRT_CFLAGS)