diff --git a/ios/build_framework.py b/ios/build_framework.py
index 11d9a21276..3f0e85f725 100755
--- a/ios/build_framework.py
+++ b/ios/build_framework.py
@@ -13,16 +13,16 @@ Script will create <outputdir>, if it's missing, and a few its subdirectories:
 
     <outputdir>
         build/
-            iPhoneOS/
+            iPhoneOS-*/
                [cmake-generated build tree for an iOS device target]
             iPhoneSimulator/
                [cmake-generated build tree for iOS simulator]
-        OpenCV.framework/
+        opencv2.framework/
             [the framework content]
 
 The script should handle minor OpenCV updates efficiently
 - it does not recompile the library from scratch each time.
-However, OpenCV.framework directory is erased and recreated on each run.
+However, opencv2.framework directory is erased and recreated on each run.
 """
 
 import glob, re, os, os.path, shutil, string, sys
diff --git a/ios/cmake/Modules/Platform/iOS.cmake b/ios/cmake/Modules/Platform/iOS.cmake
index 9d6ab80913..4d196e65d9 100644
--- a/ios/cmake/Modules/Platform/iOS.cmake
+++ b/ios/cmake/Modules/Platform/iOS.cmake
@@ -40,7 +40,7 @@ set (CMAKE_CXX_OSX_CURRENT_VERSION_FLAG "${CMAKE_C_OSX_CURRENT_VERSION_FLAG}")
 
 # Hidden visibilty is required for cxx on iOS
 set (CMAKE_C_FLAGS "")
-set (CMAKE_CXX_FLAGS "-headerpad_max_install_names -fvisibility=hidden -fvisibility-inlines-hidden")
+set (CMAKE_CXX_FLAGS "-stdlib=libc++ -headerpad_max_install_names -fvisibility=hidden -fvisibility-inlines-hidden")
 
 set (CMAKE_CXX_FLAGS_RELEASE "-DNDEBUG -O3 -fomit-frame-pointer -ffast-math")
 
diff --git a/ios/cmake/Toolchains/Toolchain-iPhoneOS_Xcode.cmake b/ios/cmake/Toolchains/Toolchain-iPhoneOS_Xcode.cmake
index aa3a67cdbd..67343253bd 100644
--- a/ios/cmake/Toolchains/Toolchain-iPhoneOS_Xcode.cmake
+++ b/ios/cmake/Toolchains/Toolchain-iPhoneOS_Xcode.cmake
@@ -8,8 +8,8 @@ set (CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_CURRENT_SOURCE_DIR}/ios/cma
 
 # Force the compilers to gcc for iOS
 include (CMakeForceCompiler)
-CMAKE_FORCE_C_COMPILER (gcc gcc)
-CMAKE_FORCE_CXX_COMPILER (g++ g++)
+#CMAKE_FORCE_C_COMPILER (gcc gcc)
+#CMAKE_FORCE_CXX_COMPILER (g++ g++)
 
 set (CMAKE_C_SIZEOF_DATA_PTR 4)
 set (CMAKE_C_HAS_ISYSROOT 1)
diff --git a/ios/cmake/Toolchains/Toolchain-iPhoneSimulator_Xcode.cmake b/ios/cmake/Toolchains/Toolchain-iPhoneSimulator_Xcode.cmake
index 78d45bca18..7ef8113edb 100644
--- a/ios/cmake/Toolchains/Toolchain-iPhoneSimulator_Xcode.cmake
+++ b/ios/cmake/Toolchains/Toolchain-iPhoneSimulator_Xcode.cmake
@@ -8,8 +8,8 @@ set (CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_CURRENT_SOURCE_DIR}/ios/cma
 
 # Force the compilers to gcc for iOS
 include (CMakeForceCompiler)
-CMAKE_FORCE_C_COMPILER (gcc gcc)
-CMAKE_FORCE_CXX_COMPILER (g++ g++)
+#CMAKE_FORCE_C_COMPILER (gcc gcc)
+#CMAKE_FORCE_CXX_COMPILER (g++ g++)
 
 set (CMAKE_C_SIZEOF_DATA_PTR 4)
 set (CMAKE_C_HAS_ISYSROOT 1)
diff --git a/modules/core/include/opencv2/core/operations.hpp b/modules/core/include/opencv2/core/operations.hpp
index 2f5f9205cf..74263022ee 100644
--- a/modules/core/include/opencv2/core/operations.hpp
+++ b/modules/core/include/opencv2/core/operations.hpp
@@ -56,7 +56,10 @@
   #define CV_XADD(addr,delta) _InterlockedExchangeAdd(const_cast<void*>(reinterpret_cast<volatile void*>(addr)), delta)
 #elif defined __GNUC__
 
-  #if __GNUC__*10 + __GNUC_MINOR__ >= 42
+  #if defined __clang__ && __clang_major__ >= 3 && defined __ATOMIC_SEQ_CST
+    #define CV_XADD(addr, delta) __c11_atomic_fetch_add((_Atomic(int)*)(addr), (delta), __ATOMIC_SEQ_CST)
+
+  #elif __GNUC__*10 + __GNUC_MINOR__ >= 42
 
     #if !defined WIN32 && (defined __i486__ || defined __i586__ || \
         defined __i686__ || defined __MMX__ || defined __SSE__  || defined __ppc__)
@@ -2460,18 +2463,10 @@ dot(const Vector<_Tp>& v1, const Vector<_Tp>& v2)
     assert(v1.size() == v2.size());
 
     _Tw s = 0;
-    if( n > 0 )
-    {
-        const _Tp *ptr1 = &v1[0], *ptr2 = &v2[0];
-     #if CV_ENABLE_UNROLLED
-        const size_t n2 = (n > 4) ? n : 4;
-        for(; i <= n2 - 4; i += 4 )
-            s += (_Tw)ptr1[i]*ptr2[i] + (_Tw)ptr1[i+1]*ptr2[i+1] +
-                (_Tw)ptr1[i+2]*ptr2[i+2] + (_Tw)ptr1[i+3]*ptr2[i+3];
-    #endif
-        for( ; i < n; i++ )
-            s += (_Tw)ptr1[i]*ptr2[i];
-    }
+    const _Tp *ptr1 = &v1[0], *ptr2 = &v2[0];
+    for( ; i < n; i++ )
+        s += (_Tw)ptr1[i]*ptr2[i];
+
     return s;
 }