diff --git a/cmake/Modules/HandleCompilerRT.cmake b/cmake/Modules/HandleCompilerRT.cmake
--- a/cmake/Modules/HandleCompilerRT.cmake
+++ b/cmake/Modules/HandleCompilerRT.cmake
@@ -20,8 +20,17 @@
     if(NOT name MATCHES "builtins.*")
       set(component_name "${name}_")
     endif()
-    # TODO: Support ios, tvos and watchos as well.
-    set(component_name "${component_name}osx")
+    if (CMAKE_OSX_SYSROOT MATCHES ".+MacOSX.+")
+      set(component_name "${component_name}osx")
+    elseif (CMAKE_OSX_SYSROOT MATCHES ".+iPhoneOS.+")
+      set(component_name "${component_name}ios")
+    elseif (CMAKE_OSX_SYSROOT MATCHES ".+AppleTVOS.+")
+      set(component_name "${component_name}tvos")
+    elseif (CMAKE_OSX_SYSROOT MATCHES ".+WatchOS.+")
+      set(component_name "${component_name}watchos")
+    else()
+      message(FATAL_ERROR "Unknown Apple SDK ${CMAKE_OSX_SYSROOT}, we don't know which compiler-rt library suffix to use.")
+    endif()
   else()
     set(component_name "${name}")
   endif()