diff -up mongodb-src-r2.4.5/src/mongo/bson/util/atomic_int.h.atomics mongodb-src-r2.4.5/src/mongo/bson/util/atomic_int.h
--- mongodb-src-r2.4.5/src/mongo/bson/util/atomic_int.h.atomics	2013-07-02 15:27:08.000000000 -0400
+++ mongodb-src-r2.4.5/src/mongo/bson/util/atomic_int.h	2013-07-11 10:20:25.474610585 -0400
@@ -24,6 +24,10 @@
 
 #include "mongo/platform/compiler.h"
 
+#define GCC_VERSION (__GNUC__ * 10000                 \
+                     + __GNUC_MINOR__ * 100           \
+                     + __GNUC_PATCHLEVEL__)
+
 namespace mongo {
 
     /**
@@ -72,6 +76,28 @@ namespace mongo {
         InterlockedAdd((volatile long *)&x,by);
     }
 # endif
+#elif defined(GCC_VERSION) && GCC_VERSION >= 40700
+// in GCC version >= 4.7.0 we can use the built-in atomic operations
+
+    inline void AtomicUInt::set(unsigned newX) {
+        __atomic_store_n (&x, newX, __ATOMIC_SEQ_CST);
+    }
+    AtomicUInt AtomicUInt::operator++() {    // ++prefix
+        return __atomic_add_fetch(&x, 1, __ATOMIC_SEQ_CST);
+    }
+    AtomicUInt AtomicUInt::operator++(int) { // postfix++
+        return __atomic_fetch_add(&x, 1, __ATOMIC_SEQ_CST);
+    }
+    AtomicUInt AtomicUInt::operator--() {    // --prefix
+        return __atomic_add_fetch(&x, -1, __ATOMIC_SEQ_CST);
+    }
+    AtomicUInt AtomicUInt::operator--(int) { // postfix--
+        return __atomic_fetch_add(&x, -1, __ATOMIC_SEQ_CST);
+    }
+    void AtomicUInt::signedAdd(int by) {
+        __atomic_fetch_add(&x, by, __ATOMIC_SEQ_CST);
+    }
+
 #elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
     // this is in GCC >= 4.1
     inline void AtomicUInt::set(unsigned newX) { __sync_synchronize(); x = newX; }
diff -up mongodb-src-r2.4.5/src/mongo/platform/atomic_intrinsics_gcc.h.atomics mongodb-src-r2.4.5/src/mongo/platform/atomic_intrinsics_gcc.h
--- mongodb-src-r2.4.5/src/mongo/platform/atomic_intrinsics_gcc.h.atomics	2013-07-02 15:27:08.000000000 -0400
+++ mongodb-src-r2.4.5/src/mongo/platform/atomic_intrinsics_gcc.h	2013-07-11 10:20:25.479611190 -0400
@@ -14,16 +14,60 @@
  */
 
 /**
- * Implementation of the AtomicIntrinsics<T>::* operations for IA-32 and AMD64 systems using a
- * GCC-compatible compiler toolchain.
+ * Implementation of the AtomicIntrinsics<T>::* operations for GCC-compatible compiler toolchain.
  */
 
 #pragma once
 
 #include <boost/utility.hpp>
 
+#define GCC_VERSION (__GNUC__ * 10000                 \
+                     + __GNUC_MINOR__ * 100           \
+                     + __GNUC_PATCHLEVEL__)
+
 namespace mongo {
 
+// If GCC version >= 4.7.0, we can use the built-in atomic operations
+#if defined(GCC_VERSION) && GCC_VERSION >= 40700
+
+    /**
+     * Instantiation of AtomicIntrinsics<>.
+     */
+    template <typename T>
+    class AtomicIntrinsics {
+    public:
+
+        static T compareAndSwap(volatile T* dest, T expected, T newValue) {
+            return __atomic_compare_exchange_n (dest, &expected, newValue, 0, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
+        }
+
+        static T swap(volatile T* dest, T newValue) {
+            return __atomic_exchange_n (dest, newValue, __ATOMIC_SEQ_CST);
+        }
+
+        static T load(volatile const T* value) {
+            return __atomic_load_n (value, __ATOMIC_SEQ_CST);
+        }
+
+        static T loadRelaxed(volatile const T* value) {
+            return *value;
+        }
+
+        static void store(volatile T* dest, T newValue) {
+            __atomic_store_n (dest, newValue, __ATOMIC_SEQ_CST);
+        }
+
+        static T fetchAndAdd(volatile T* dest, T increment) {
+            return __atomic_fetch_add (dest, increment, __ATOMIC_SEQ_CST);
+        }
+
+    private:
+        AtomicIntrinsics();
+        ~AtomicIntrinsics();
+    };
+
+#else // GCC version < 4.7, so we must use legacy (platform-specific) atomic operations
+
     /**
      * Instantiation of AtomicIntrinsics<> for all word types T where sizeof<T> <= sizeof(void *).
      *
@@ -163,4 +207,6 @@ namespace mongo {
         ~AtomicIntrinsics();
     };
 
+#endif // GCC_VERSION >= 40700
+
 }  // namespace mongo
diff -up mongodb-src-r2.4.5/src/mongo/platform/bits.h.atomics mongodb-src-r2.4.5/src/mongo/platform/bits.h
--- mongodb-src-r2.4.5/src/mongo/platform/bits.h.atomics	2013-07-02 15:27:08.000000000 -0400
+++ mongodb-src-r2.4.5/src/mongo/platform/bits.h	2013-07-11 10:20:25.484611795 -0400
@@ -21,7 +21,7 @@
 
 #if defined(__x86_64__) || defined(__amd64__) || defined(_WIN64)
 #define MONGO_PLATFORM_64
-#elif defined(__i386__) || defined(_WIN32)
+#elif defined(__i386__) || defined(_WIN32) || defined(__arm__)
 #define MONGO_PLATFORM_32
 #else
 #error "unknown platform"