diff --git a/React/Base/RCTAssert.h b/React/Base/RCTAssert.h
index 7e73aed7d..b0a3c5c52 100644
--- a/React/Base/RCTAssert.h
+++ b/React/Base/RCTAssert.h
@@ -9,21 +9,7 @@
 
 #import <Foundation/Foundation.h>
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-/**
- * By default, only raise an NSAssertion in debug mode
- * (custom assert functions will still be called).
- */
-#ifndef RCT_ASSERT
-#if DEBUG
-#define RCT_ASSERT 1
-#else
-#define RCT_ASSERT 0
-#endif
-#endif
+#import "RCTDefines.h"
 
 /**
  * The default error domain to be used for React errors.
@@ -44,13 +30,14 @@ typedef void (^RCTAssertFunction)(
 /**
  * Private logging function - ignore this.
  */
-void _RCTAssertFormat(BOOL, const char *, int, const char *, NSString *, ...) NS_FORMAT_FUNCTION(5,6);
+RCT_EXTERN void _RCTAssertFormat(
+  BOOL, const char *, int, const char *, NSString *, ...) NS_FORMAT_FUNCTION(5,6);
 
 /**
  * This is the main assert macro that you should use.
  */
 #define RCTAssert(condition, ...) do { BOOL pass = ((condition) != 0); \
-if (RCT_ASSERT && !pass) { [[NSAssertionHandler currentHandler] handleFailureInFunction:@(__func__) \
+if (RCT_NSASSERT && !pass) { [[NSAssertionHandler currentHandler] handleFailureInFunction:@(__func__) \
 file:@(__FILE__) lineNumber:__LINE__ description:__VA_ARGS__]; } \
 _RCTAssertFormat(pass, __FILE__, __LINE__, __func__, __VA_ARGS__); \
 } while (false)
@@ -66,16 +53,12 @@ _RCTAssertFormat(pass, __FILE__, __LINE__, __func__, __VA_ARGS__); \
  * macros. You can use these to replace the standard behavior with custom log
  * functionality.
  */
-void RCTSetAssertFunction(RCTAssertFunction assertFunction);
-RCTAssertFunction RCTGetAssertFunction(void);
+RCT_EXTERN void RCTSetAssertFunction(RCTAssertFunction assertFunction);
+RCT_EXTERN RCTAssertFunction RCTGetAssertFunction(void);
 
 /**
  * This appends additional code to the existing assert function, without
  * replacing the existing functionality. Useful if you just want to forward
  * assert info to an extra service without changing the default behavior.
  */
-void RCTAddAssertFunction(RCTAssertFunction assertFunction);
-
-#ifdef __cplusplus
-}
-#endif
+RCT_EXTERN void RCTAddAssertFunction(RCTAssertFunction assertFunction);
diff --git a/React/Base/RCTBridge.h b/React/Base/RCTBridge.h
index 0a82b05e2..a37b9ac7d 100644
--- a/React/Base/RCTBridge.h
+++ b/React/Base/RCTBridge.h
@@ -10,6 +10,7 @@
 #import <UIKit/UIKit.h>
 
 #import "RCTBridgeModule.h"
+#import "RCTDefines.h"
 #import "RCTFrameUpdate.h"
 #import "RCTInvalidating.h"
 #import "RCTJavaScriptExecutor.h"
@@ -40,7 +41,7 @@ typedef NSArray *(^RCTBridgeModuleProviderBlock)(void);
 /**
  * This function returns the module name for a given class.
  */
-extern NSString *RCTBridgeModuleNameForClass(Class bridgeModuleClass);
+RCT_EXTERN NSString *RCTBridgeModuleNameForClass(Class bridgeModuleClass);
 
 /**
  * Async batched bridge used to communicate with the JavaScript application.
diff --git a/React/Base/RCTBridge.m b/React/Base/RCTBridge.m
index 31a8bea77..40dfceec8 100644
--- a/React/Base/RCTBridge.m
+++ b/React/Base/RCTBridge.m
@@ -143,7 +143,8 @@ static NSArray *RCTBridgeModuleClassesByModuleID(void)
 
         // Get data entry
         NSString *entry = @(*(const char **)(mach_header + addr));
-        NSArray *parts = [[entry substringWithRange:(NSRange){2, entry.length - 3}] componentsSeparatedByString:@" "];
+        NSArray *parts = [[entry substringWithRange:(NSRange){2, entry.length - 3}]
+                          componentsSeparatedByString:@" "];
 
         // Parse class name
         NSString *moduleClassName = parts[0];
@@ -164,33 +165,32 @@ static NSArray *RCTBridgeModuleClassesByModuleID(void)
       }
     }
 
-#if DEBUG
+    if (RCT_DEBUG) {
 
-    // We may be able to get rid of this check in future, once people
-    // get used to the new registration system. That would potentially
-    // allow you to create modules that are not automatically registered
+      // We may be able to get rid of this check in future, once people
+      // get used to the new registration system. That would potentially
+      // allow you to create modules that are not automatically registered
 
-    static unsigned int classCount;
-    Class *classes = objc_copyClassList(&classCount);
-    for (unsigned int i = 0; i < classCount; i++)
-    {
-      Class cls = classes[i];
-      Class superclass = cls;
-      while (superclass)
+      static unsigned int classCount;
+      Class *classes = objc_copyClassList(&classCount);
+      for (unsigned int i = 0; i < classCount; i++)
       {
-        if (class_conformsToProtocol(superclass, @protocol(RCTBridgeModule)))
+        Class cls = classes[i];
+        Class superclass = cls;
+        while (superclass)
         {
-          if (![RCTModuleClassesByID containsObject:cls]) {
-            RCTLogError(@"Class %@ was not exported. Did you forget to use RCT_EXPORT_MODULE()?", NSStringFromClass(cls));
+          if (class_conformsToProtocol(superclass, @protocol(RCTBridgeModule)))
+          {
+            if (![RCTModuleClassesByID containsObject:cls]) {
+              RCTLogError(@"Class %@ was not exported. Did you forget to use RCT_EXPORT_MODULE()?", NSStringFromClass(cls));
+            }
+            break;
           }
-          break;
+          superclass = class_getSuperclass(superclass);
         }
-        superclass = class_getSuperclass(superclass);
       }
     }
 
-#endif
-
   });
 
   return RCTModuleClassesByID;
@@ -289,13 +289,13 @@ static NSString *RCTStringUpToFirstArgument(NSString *methodName)
     _isClassMethod = [reactMethodName characterAtIndex:0] == '+';
     _moduleClass = NSClassFromString(_moduleClassName);
 
-#if DEBUG
+    if (RCT_DEBUG) {
 
-    // Sanity check
-    RCTAssert([_moduleClass conformsToProtocol:@protocol(RCTBridgeModule)],
-              @"You are attempting to export the method %@, but %@ does not \
-              conform to the RCTBridgeModule Protocol", objCMethodName, _moduleClassName);
-#endif
+      // Sanity check
+      RCTAssert([_moduleClass conformsToProtocol:@protocol(RCTBridgeModule)],
+                @"You are attempting to export the method %@, but %@ does not \
+                conform to the RCTBridgeModule Protocol", objCMethodName, _moduleClassName);
+    }
 
     // Get method signature
     _methodSignature = _isClassMethod ?
@@ -449,20 +449,19 @@ static NSString *RCTStringUpToFirstArgument(NSString *methodName)
                arguments:(NSArray *)arguments
                  context:(NSNumber *)context
 {
+  if (RCT_DEBUG) {
 
-#if DEBUG
+    // Sanity check
+    RCTAssert([module class] == _moduleClass, @"Attempted to invoke method \
+              %@ on a module of class %@", _methodName, [module class]);
 
-  // Sanity check
-  RCTAssert([module class] == _moduleClass, @"Attempted to invoke method \
-            %@ on a module of class %@", _methodName, [module class]);
-#endif
-
-  // Safety check
-  if (arguments.count != _argumentBlocks.count) {
-    RCTLogError(@"%@.%@ was called with %zd arguments, but expects %zd",
-                RCTBridgeModuleNameForClass(_moduleClass), _JSMethodName,
-                arguments.count, _argumentBlocks.count);
-    return;
+    // Safety check
+    if (arguments.count != _argumentBlocks.count) {
+      RCTLogError(@"%@.%@ was called with %zd arguments, but expects %zd",
+                  RCTBridgeModuleNameForClass(_moduleClass), _JSMethodName,
+                  arguments.count, _argumentBlocks.count);
+      return;
+    }
   }
 
   // Create invocation (we can't re-use this as it wouldn't be thread-safe)
diff --git a/React/Base/RCTConvert.h b/React/Base/RCTConvert.h
index 22cc7ec81..e664f06e0 100644
--- a/React/Base/RCTConvert.h
+++ b/React/Base/RCTConvert.h
@@ -16,6 +16,7 @@
 #import "../Views/RCTAnimationType.h"
 #import "../Views/RCTPointerEvents.h"
 
+#import "RCTDefines.h"
 #import "RCTLog.h"
 
 /**
@@ -116,33 +117,25 @@ typedef BOOL css_overflow;
 
 @end
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 /**
  * This function will attempt to set a property using a json value by first
  * inferring the correct type from all available information, and then
  * applying an appropriate conversion method. If the property does not
  * exist, or the type cannot be inferred, the function will return NO.
  */
-BOOL RCTSetProperty(id target, NSString *keyPath, SEL type, id json);
+RCT_EXTERN BOOL RCTSetProperty(id target, NSString *keyPath, SEL type, id json);
 
 /**
  * This function attempts to copy a property from the source object to the
  * destination object using KVC. If the property does not exist, or cannot
  * be set, it will do nothing and return NO.
  */
-BOOL RCTCopyProperty(id target, id source, NSString *keyPath);
+RCT_EXTERN BOOL RCTCopyProperty(id target, id source, NSString *keyPath);
 
 /**
  * Underlying implementation of RCT_ENUM_CONVERTER macro. Ignore this.
  */
-NSNumber *RCTConvertEnumValue(const char *, NSDictionary *, NSNumber *, id);
-
-#ifdef __cplusplus
-}
-#endif
+RCT_EXTERN NSNumber *RCTConvertEnumValue(const char *, NSDictionary *, NSNumber *, id);
 
 /**
  * This macro is used for creating simple converter functions that just call
diff --git a/React/Base/RCTDefines.h b/React/Base/RCTDefines.h
new file mode 100644
index 000000000..71550a30d
--- /dev/null
+++ b/React/Base/RCTDefines.h
@@ -0,0 +1,55 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import <Foundation/Foundation.h>
+
+/**
+ * Make global functions usable in C++
+ */
+#if defined(__cplusplus)
+#define RCT_EXTERN extern "C" __attribute__((visibility("default")))
+#else
+#define RCT_EXTERN extern __attribute__((visibility("default")))
+#endif
+
+/**
+ * The RCT_DEBUG macro can be used to exclude error checking and logging code
+ * from release builds to improve performance and reduce binary size.
+ */
+#ifndef RCT_DEBUG
+#if DEBUG
+#define RCT_DEBUG 1
+#else
+#define RCT_DEBUG 0
+#endif
+#endif
+
+/**
+ * The RCT_DEV macro can be used to enable or disable development tools
+ * such as the debug executors, dev menu, red box, etc.
+ */
+#ifndef RCT_DEV
+#if DEBUG
+#define RCT_DEV 1
+#else
+#define RCT_DEV 0
+#endif
+#endif
+
+/**
+ * By default, only raise an NSAssertion in debug mode
+ * (custom assert functions will still be called).
+ */
+#ifndef RCT_NSASSERT
+#if RCT_DEBUG
+#define RCT_NSASSERT 1
+#else
+#define RCT_NSASSERT 0
+#endif
+#endif
diff --git a/React/Base/RCTLog.h b/React/Base/RCTLog.h
index 3a8a70d5b..7fa25e6a8 100644
--- a/React/Base/RCTLog.h
+++ b/React/Base/RCTLog.h
@@ -10,10 +10,7 @@
 #import <Foundation/Foundation.h>
 
 #import "RCTAssert.h"
-
-#ifdef __cplusplus
-extern "C" {
-#endif
+#import "RCTDefines.h"
 
 /**
  * Thresholds for logs to raise an assertion, or display redbox, respectively.
@@ -46,9 +43,9 @@ typedef void (^RCTLogFunction)(
 );
 
 /**
- * Get a given thread's name (or the current queue, iff in debug mode)
+ * Get a given thread's name (or the current queue, if in debug mode)
  */
-NSString *RCTThreadName(NSThread *);
+RCT_EXTERN NSString *RCTThreadName(NSThread *);
 
 /**
  * A method to generate a string from a collection of log data. To omit any
@@ -73,35 +70,35 @@ extern RCTLogFunction RCTDefaultLogFunction;
  * below which logs will be ignored. Default is RCTLogLevelInfo for debug and
  * RCTLogLevelError for production.
  */
-void RCTSetLogThreshold(RCTLogLevel threshold);
-RCTLogLevel RCTGetLogThreshold(void);
+RCT_EXTERN void RCTSetLogThreshold(RCTLogLevel threshold);
+RCT_EXTERN RCTLogLevel RCTGetLogThreshold(void);
 
 /**
  * These methods get and set the current logging function called by the RCTLogXX
  * macros. You can use these to replace the standard behavior with custom log
  * functionality.
  */
-void RCTSetLogFunction(RCTLogFunction logFunction);
-RCTLogFunction RCTGetLogFunction(void);
+RCT_EXTERN void RCTSetLogFunction(RCTLogFunction logFunction);
+RCT_EXTERN RCTLogFunction RCTGetLogFunction(void);
 
 /**
  * This appends additional code to the existing log function, without replacing
  * the existing functionality. Useful if you just want to forward logs to an
  * extra service without changing the default behavior.
  */
-void RCTAddLogFunction(RCTLogFunction logFunction);
+RCT_EXTERN void RCTAddLogFunction(RCTLogFunction logFunction);
 
 /**
  * This method adds a conditional prefix to any messages logged within the scope
  * of the passed block. This is useful for adding additional context to log
  * messages. The block will be performed synchronously on the current thread.
  */
-void RCTPerformBlockWithLogPrefix(void (^block)(void), NSString *prefix);
+RCT_EXTERN void RCTPerformBlockWithLogPrefix(void (^block)(void), NSString *prefix);
 
 /**
  * Private logging functions - ignore these.
  */
-void _RCTLogFormat(RCTLogLevel, const char *, int, NSString *, ...) NS_FORMAT_FUNCTION(4,5);
+RCT_EXTERN void _RCTLogFormat(RCTLogLevel, const char *, int, NSString *, ...) NS_FORMAT_FUNCTION(4,5);
 #define _RCTLog(lvl, ...) do { \
   if (lvl >= RCTLOG_FATAL_LEVEL) { RCTAssert(NO, __VA_ARGS__); } \
   _RCTLogFormat(lvl, __FILE__, __LINE__, __VA_ARGS__); \
@@ -116,7 +113,3 @@ void _RCTLogFormat(RCTLogLevel, const char *, int, NSString *, ...) NS_FORMAT_FU
 #define RCTLogWarn(...) _RCTLog(RCTLogLevelWarning, __VA_ARGS__)
 #define RCTLogError(...) _RCTLog(RCTLogLevelError, __VA_ARGS__)
 #define RCTLogMustFix(...) _RCTLog(RCTLogLevelMustFix, __VA_ARGS__)
-
-#ifdef __cplusplus
-}
-#endif
diff --git a/React/Base/RCTLog.m b/React/Base/RCTLog.m
index 449980fc3..6ca2d4eb8 100644
--- a/React/Base/RCTLog.m
+++ b/React/Base/RCTLog.m
@@ -11,6 +11,7 @@
 
 #import "RCTAssert.h"
 #import "RCTBridge.h"
+#import "RCTDefines.h"
 #import "RCTRedBox.h"
 
 @interface RCTBridge (Logging)
@@ -36,7 +37,7 @@ static void RCTLogSetup()
 {
   RCTCurrentLogFunction = RCTDefaultLogFunction;
 
-#if DEBUG
+#if RCT_DEBUG
   RCTCurrentLogThreshold = RCTLogLevelInfo - 1;
 #else
   RCTCurrentLogThreshold = RCTLogLevelError;
@@ -102,7 +103,7 @@ NSString *RCTThreadName(NSThread *thread)
 {
   NSString *threadName = [thread isMainThread] ? @"main" : thread.name;
   if (threadName.length == 0) {
-#if DEBUG
+#if DEBUG // This is DEBUG not RCT_DEBUG because it *really* must not ship in RC
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
     threadName = @(dispatch_queue_get_label(dispatch_get_current_queue()));
@@ -161,12 +162,7 @@ void _RCTLogFormat(
   NSString *format, ...)
 {
 
-#if DEBUG
-  BOOL log = YES;
-#else
-  BOOL log = (RCTCurrentLogFunction != nil);
-#endif
-
+  BOOL log = RCT_DEBUG || (RCTCurrentLogFunction != nil);
   if (log && level >= RCTCurrentLogThreshold) {
 
     // Get message
@@ -188,17 +184,15 @@ void _RCTLogFormat(
       level, fileName ? @(fileName) : nil, (lineNumber >= 0) ? @(lineNumber) : nil, message
     );
 
-#if DEBUG
+    if (RCT_DEBUG) {
 
-    // Log to red box
-    if (level >= RCTLOG_REDBOX_LEVEL) {
-      [[RCTRedBox sharedInstance] showErrorMessage:message];
+      // Log to red box
+      if (level >= RCTLOG_REDBOX_LEVEL) {
+        [[RCTRedBox sharedInstance] showErrorMessage:message];
+      }
+
+      // Log to JS executor
+      [RCTBridge logMessage:message level:level ? @(RCTLogLevels[level - 1]) : @"info"];
     }
-
-    // Log to JS executor
-    [RCTBridge logMessage:message level:level ? @(RCTLogLevels[level - 1]) : @"info"];
-
-#endif
-
   }
 }
diff --git a/React/Base/RCTProfile.h b/React/Base/RCTProfile.h
index b3a1683d1..0c254c80a 100644
--- a/React/Base/RCTProfile.h
+++ b/React/Base/RCTProfile.h
@@ -9,45 +9,47 @@
 
 #import <Foundation/Foundation.h>
 
+#import "RCTDefines.h"
+
 /**
  * RCTProfile
  *
  * This file provides a set of functions and macros for performance profiling
  *
- * NOTE: This API is a work in a work in progress, please consider it before
- * before using.
+ * NOTE: This API is a work in a work in progress, please consider carefully
+ * before before using it.
  */
 
-#if DEBUG
+#if RCT_DEV
 
 /**
  * Returns YES if the profiling information is currently being collected
  */
-BOOL RCTProfileIsProfiling(void);
+RCT_EXTERN BOOL RCTProfileIsProfiling(void);
 
 /**
  * Start collecting profiling information
  */
-void RCTProfileInit(void);
+RCT_EXTERN void RCTProfileInit(void);
 
 /**
  * Stop profiling and return a JSON string of the collected data - The data
  * returned is compliant with google's trace event format - the format used
  * as input to trace-viewer
  */
-NSString *RCTProfileEnd(void);
+RCT_EXTERN NSString *RCTProfileEnd(void);
 
 /**
  * Collects the initial event information for the event and returns a reference ID
  */
-NSNumber *_RCTProfileBeginEvent(void);
+RCT_EXTERN NSNumber *_RCTProfileBeginEvent(void);
 
 /**
  * The ID returned by BeginEvent should then be passed into EndEvent, with the
  * rest of the event information. Just at this point the event will actually be
  * registered
  */
-void _RCTProfileEndEvent(NSNumber *, NSString *, NSString *, id);
+RCT_EXTERN void _RCTProfileEndEvent(NSNumber *, NSString *, NSString *, id);
 
 /**
  * This pair of macros implicitly handle the event ID when beginning and ending
@@ -69,7 +71,7 @@ _RCTProfileEndEvent(__rct_profile_id, name, category, args)
 /**
  * An event that doesn't have a duration (i.e. Notification, VSync, etc)
  */
-void RCTProfileImmediateEvent(NSString *, NSTimeInterval , NSString *);
+RCT_EXTERN void RCTProfileImmediateEvent(NSString *, NSTimeInterval , NSString *);
 
 /**
  * Helper to profile the duration of the execution of a block. This method uses
diff --git a/React/Base/RCTProfile.m b/React/Base/RCTProfile.m
index 71d34551e..929a026a9 100644
--- a/React/Base/RCTProfile.m
+++ b/React/Base/RCTProfile.m
@@ -13,10 +13,11 @@
 
 #import <UIKit/UIKit.h>
 
+#import "RCTDefines.h"
 #import "RCTLog.h"
 #import "RCTUtils.h"
 
-#if DEBUG
+#if RCT_DEV
 
 #pragma mark - Prototypes
 
diff --git a/React/Base/RCTRedBox.m b/React/Base/RCTRedBox.m
index 3bed31505..882a87bfe 100644
--- a/React/Base/RCTRedBox.m
+++ b/React/Base/RCTRedBox.m
@@ -282,23 +282,14 @@
 
 - (void)showErrorMessage:(NSString *)message withStack:(NSArray *)stack showIfHidden:(BOOL)shouldShow
 {
-
-#if DEBUG
-
-  dispatch_block_t block = ^{
-    if (!_window) {
-      _window = [[RCTRedBoxWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
-    }
-    [_window showErrorMessage:message withStack:stack showIfHidden:shouldShow];
-  };
-  if ([NSThread isMainThread]) {
-    block();
-  } else {
-    dispatch_async(dispatch_get_main_queue(), block);
+  if (RCT_DEBUG) {
+    dispatch_async(dispatch_get_main_queue(), ^{
+      if (!_window) {
+        _window = [[RCTRedBoxWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
+      }
+      [_window showErrorMessage:message withStack:stack showIfHidden:shouldShow];
+    });
   }
-
-#endif
-
 }
 
 - (NSString *)currentErrorMessage
diff --git a/React/Base/RCTUtils.h b/React/Base/RCTUtils.h
index d20ba8a5f..812a65122 100644
--- a/React/Base/RCTUtils.h
+++ b/React/Base/RCTUtils.h
@@ -13,43 +13,36 @@
 #import <Foundation/Foundation.h>
 
 #import "RCTAssert.h"
-
-#ifdef __cplusplus
-extern "C" {
-#endif
+#import "RCTDefines.h"
 
 // Utility functions for JSON object <-> string serialization/deserialization
-NSString *RCTJSONStringify(id jsonObject, NSError **error);
-id RCTJSONParse(NSString *jsonString, NSError **error);
+RCT_EXTERN NSString *RCTJSONStringify(id jsonObject, NSError **error);
+RCT_EXTERN id RCTJSONParse(NSString *jsonString, NSError **error);
 
 // Get MD5 hash of a string (TODO: currently unused. Remove?)
-NSString *RCTMD5Hash(NSString *string);
+RCT_EXTERN NSString *RCTMD5Hash(NSString *string);
 
 // Get screen metrics in a thread-safe way
-CGFloat RCTScreenScale(void);
-CGSize RCTScreenSize(void);
+RCT_EXTERN CGFloat RCTScreenScale(void);
+RCT_EXTERN CGSize RCTScreenSize(void);
 
 // Round float coordinates to nearest whole screen pixel (not point)
-CGFloat RCTRoundPixelValue(CGFloat value);
-CGFloat RCTCeilPixelValue(CGFloat value);
-CGFloat RCTFloorPixelValue(CGFloat value);
+RCT_EXTERN CGFloat RCTRoundPixelValue(CGFloat value);
+RCT_EXTERN CGFloat RCTCeilPixelValue(CGFloat value);
+RCT_EXTERN CGFloat RCTFloorPixelValue(CGFloat value);
 
 // Get current time, for precise performance metrics
-NSTimeInterval RCTTGetAbsoluteTime(void);
+RCT_EXTERN NSTimeInterval RCTTGetAbsoluteTime(void);
 
 // Method swizzling
-void RCTSwapClassMethods(Class cls, SEL original, SEL replacement);
-void RCTSwapInstanceMethods(Class cls, SEL original, SEL replacement);
+RCT_EXTERN void RCTSwapClassMethods(Class cls, SEL original, SEL replacement);
+RCT_EXTERN void RCTSwapInstanceMethods(Class cls, SEL original, SEL replacement);
 
 // Module subclass support
-BOOL RCTClassOverridesClassMethod(Class cls, SEL selector);
-BOOL RCTClassOverridesInstanceMethod(Class cls, SEL selector);
+RCT_EXTERN BOOL RCTClassOverridesClassMethod(Class cls, SEL selector);
+RCT_EXTERN BOOL RCTClassOverridesInstanceMethod(Class cls, SEL selector);
 
 // Creates a standardized error object
 // TODO(#6472857): create NSErrors and automatically convert them over the bridge.
-NSDictionary *RCTMakeError(NSString *message, id toStringify, NSDictionary *extraData);
-NSDictionary *RCTMakeAndLogError(NSString *message, id toStringify, NSDictionary *extraData);
-
-#ifdef __cplusplus
-}
-#endif
+RCT_EXTERN NSDictionary *RCTMakeError(NSString *message, id toStringify, NSDictionary *extraData);
+RCT_EXTERN NSDictionary *RCTMakeAndLogError(NSString *message, id toStringify, NSDictionary *extraData);
diff --git a/React/Executors/RCTContextExecutor.m b/React/Executors/RCTContextExecutor.m
index d2aac3fbe..86444dd2a 100644
--- a/React/Executors/RCTContextExecutor.m
+++ b/React/Executors/RCTContextExecutor.m
@@ -14,6 +14,7 @@
 #import <JavaScriptCore/JavaScriptCore.h>
 
 #import "RCTAssert.h"
+#import "RCTDefines.h"
 #import "RCTLog.h"
 #import "RCTProfile.h"
 #import "RCTUtils.h"
@@ -321,10 +322,9 @@ static NSError *RCTNSErrorFromJSError(JSContextRef context, JSValueRef jsError)
    asGlobalObjectNamed:(NSString *)objectName
               callback:(RCTJavaScriptCompleteBlock)onComplete
 {
-
-#if DEBUG
-  RCTAssert(RCTJSONParse(script, NULL) != nil, @"%@ wasn't valid JSON!", script);
-#endif
+  if (RCT_DEBUG) {
+    RCTAssert(RCTJSONParse(script, NULL) != nil, @"%@ wasn't valid JSON!", script);
+  }
 
   __weak RCTContextExecutor *weakSelf = self;
   [self executeBlockOnJavaScriptQueue:RCTProfileBlock((^{
diff --git a/React/Modules/RCTExceptionsManager.m b/React/Modules/RCTExceptionsManager.m
index ed30d8741..ece5d0668 100644
--- a/React/Modules/RCTExceptionsManager.m
+++ b/React/Modules/RCTExceptionsManager.m
@@ -9,6 +9,7 @@
 
 #import "RCTExceptionsManager.h"
 
+#import "RCTDefines.h"
 #import "RCTLog.h"
 #import "RCTRedBox.h"
 #import "RCTRootView.h"
@@ -43,11 +44,10 @@ RCT_EXPORT_METHOD(reportUnhandledException:(NSString *)message
     return;
   }
 
-#if DEBUG
-
-  [[RCTRedBox sharedInstance] showErrorMessage:message withStack:stack];
-
-#else
+  if (RCT_DEBUG) {
+    [[RCTRedBox sharedInstance] showErrorMessage:message withStack:stack];
+    return;
+  }
 
   static NSUInteger reloadRetries = 0;
   const NSUInteger maxMessageLength = 75;
@@ -76,21 +76,14 @@ RCT_EXPORT_METHOD(reportUnhandledException:(NSString *)message
     NSString *name = [@"Unhandled JS Exception: " stringByAppendingString:sanitizedMessage];
     [NSException raise:name format:@"Message: %@, stack: %@", message, prettyStack];
   }
-
-#endif
-
 }
 
 RCT_EXPORT_METHOD(updateExceptionMessage:(NSString *)message
                   stack:(NSArray *)stack)
 {
-
-#if DEBUG
-
-  [[RCTRedBox sharedInstance] updateErrorMessage:message withStack:stack];
-
-#endif
-
+  if (RCT_DEBUG) {
+    [[RCTRedBox sharedInstance] updateErrorMessage:message withStack:stack];
+  }
 }
 
 @end
diff --git a/React/Modules/RCTUIManager.m b/React/Modules/RCTUIManager.m
index e2dc8d560..3f3ea7596 100644
--- a/React/Modules/RCTUIManager.m
+++ b/React/Modules/RCTUIManager.m
@@ -18,6 +18,7 @@
 #import "RCTAssert.h"
 #import "RCTBridge.h"
 #import "RCTConvert.h"
+#import "RCTDefines.h"
 #import "RCTLog.h"
 #import "RCTProfile.h"
 #import "RCTRootView.h"
@@ -703,20 +704,16 @@ static BOOL RCTCallPropertySetter(NSString *key, SEL setter, id value, id view,
       ((void (*)(id, SEL, id, id, id))objc_msgSend)(manager, setter, value, view, defaultView);
     };
 
-#if DEBUG
+    if (RCT_DEBUG) {
+      NSString *viewName = RCTViewNameForModuleName(RCTBridgeModuleNameForClass([manager class]));
+      NSString *logPrefix = [NSString stringWithFormat:
+                             @"Error setting property '%@' of %@ with tag #%@: ",
+                             key, viewName, [view reactTag]];
 
-    NSString *viewName = RCTViewNameForModuleName(RCTBridgeModuleNameForClass([manager class]));
-    NSString *logPrefix = [NSString stringWithFormat:
-                           @"Error setting property '%@' of %@ with tag #%@: ",
-                           key, viewName, [view reactTag]];
-
-    RCTPerformBlockWithLogPrefix(block, logPrefix);
-
-#else
-
-    block();
-
-#endif
+      RCTPerformBlockWithLogPrefix(block, logPrefix);
+    } else {
+      block();
+    }
 
     return YES;
   }