diff --git a/llvm/cmake/platforms/iOS.cmake b/llvm/cmake/platforms/iOS.cmake
index 49140590ab2b..99692fd6d2aa 100644
--- a/llvm/cmake/platforms/iOS.cmake
+++ b/llvm/cmake/platforms/iOS.cmake
@@ -1,39 +1,26 @@
 # Toolchain config for iOS.
-#
-# Usage:
-# mkdir build; cd build
-# cmake ..; make
-# mkdir ios; cd ios
-# cmake -DLLVM_IOS_TOOLCHAIN_DIR=/path/to/ios/ndk \
-#   -DCMAKE_TOOLCHAIN_FILE=../../cmake/platforms/iOS.cmake ../..
-# make <target>
 
 SET(CMAKE_SYSTEM_NAME Darwin)
 SET(CMAKE_SYSTEM_VERSION 13)
 SET(CMAKE_CXX_COMPILER_WORKS True)
 SET(CMAKE_C_COMPILER_WORKS True)
-SET(DARWIN_TARGET_OS_NAME ios)
 
-IF(NOT DEFINED ENV{SDKROOT})
- execute_process(COMMAND xcodebuild -version -sdk iphoneos Path
-   OUTPUT_VARIABLE SDKROOT
-   ERROR_QUIET
-   OUTPUT_STRIP_TRAILING_WHITESPACE)
-ELSE()
-  execute_process(COMMAND xcodebuild -version -sdk $ENV{SDKROOT} Path
-   OUTPUT_VARIABLE SDKROOT
-   ERROR_QUIET
-   OUTPUT_STRIP_TRAILING_WHITESPACE)
-ENDIF()
+if(NOT CMAKE_OSX_SYSROOT)
+  execute_process(COMMAND xcodebuild -version -sdk iphoneos Path
+    OUTPUT_VARIABLE SDKROOT
+    ERROR_QUIET
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
 
-IF(NOT EXISTS ${SDKROOT})
-  MESSAGE(FATAL_ERROR "SDKROOT could not be detected!")
-ENDIF()
+  IF(NOT EXISTS ${SDKROOT})
+    MESSAGE(FATAL_ERROR "SDKROOT could not be detected!")
+  ENDIF()
 
-set(CMAKE_OSX_SYSROOT ${SDKROOT})
+  message(STATUS "Using SDKROOT ${SDKROOT}")
+  set(CMAKE_OSX_SYSROOT ${SDKROOT})
+endif()
 
 IF(NOT CMAKE_C_COMPILER)
-  execute_process(COMMAND xcrun -sdk ${SDKROOT} -find clang
+  execute_process(COMMAND xcrun -sdk ${CMAKE_OSX_SYSROOT} -find clang
    OUTPUT_VARIABLE CMAKE_C_COMPILER
    ERROR_QUIET
    OUTPUT_STRIP_TRAILING_WHITESPACE)
@@ -41,7 +28,7 @@ IF(NOT CMAKE_C_COMPILER)
 ENDIF()
 
 IF(NOT CMAKE_CXX_COMPILER)
-  execute_process(COMMAND xcrun -sdk ${SDKROOT} -find clang++
+  execute_process(COMMAND xcrun -sdk ${CMAKE_OSX_SYSROOT} -find clang++
    OUTPUT_VARIABLE CMAKE_CXX_COMPILER
    ERROR_QUIET
    OUTPUT_STRIP_TRAILING_WHITESPACE)
@@ -49,7 +36,7 @@ IF(NOT CMAKE_CXX_COMPILER)
 ENDIF()
 
 IF(NOT CMAKE_AR)
-  execute_process(COMMAND xcrun -sdk ${SDKROOT} -find ar
+  execute_process(COMMAND xcrun -sdk ${CMAKE_OSX_SYSROOT} -find ar
    OUTPUT_VARIABLE CMAKE_AR_val
    ERROR_QUIET
    OUTPUT_STRIP_TRAILING_WHITESPACE)
@@ -58,22 +45,10 @@ IF(NOT CMAKE_AR)
 ENDIF()
 
 IF(NOT CMAKE_RANLIB)
-  execute_process(COMMAND xcrun -sdk ${SDKROOT} -find ranlib
+  execute_process(COMMAND xcrun -sdk ${CMAKE_OSX_SYSROOT} -find ranlib
    OUTPUT_VARIABLE CMAKE_RANLIB_val
    ERROR_QUIET
    OUTPUT_STRIP_TRAILING_WHITESPACE)
   SET(CMAKE_RANLIB ${CMAKE_RANLIB_val} CACHE FILEPATH "Ranlib")
   message(STATUS "Using ranlib ${CMAKE_RANLIB}")
 ENDIF()
-
-IF (NOT DEFINED IOS_MIN_TARGET)
-execute_process(COMMAND xcodebuild -sdk ${SDKROOT} -version SDKVersion
-   OUTPUT_VARIABLE IOS_MIN_TARGET
-   ERROR_QUIET
-   OUTPUT_STRIP_TRAILING_WHITESPACE)
-ENDIF()
-
-SET(IOS_COMMON_FLAGS "-mios-version-min=${IOS_MIN_TARGET}")
-SET(CMAKE_C_FLAGS "${IOS_COMMON_FLAGS}" CACHE STRING "toolchain_cflags" FORCE)
-SET(CMAKE_CXX_FLAGS "${IOS_COMMON_FLAGS}" CACHE STRING "toolchain_cxxflags" FORCE)
-SET(CMAKE_LINK_FLAGS "${IOS_COMMON_FLAGS}" CACHE STRING "toolchain_linkflags" FORCE)