diff --git a/Configurations/Sanitizers.xcconfig b/Configurations/Sanitizers.xcconfig
index 25be668577000..accd7bf77cd6a 100644
--- a/Configurations/Sanitizers.xcconfig
+++ b/Configurations/Sanitizers.xcconfig
@@ -1,4 +1,4 @@
-// Copyright (C) 2023-2024 Apple Inc. All rights reserved.
+// Copyright (C) 2023-2025 Apple Inc. All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions
@@ -26,6 +26,8 @@
 
 // Requires SDKVariant.xcconfig.
 
+#include "WebKitTargetConditionals.xcconfig"
+
 WK_SANITIZER_GCC_OPTIMIZATION_LEVEL = $(WK_SANITIZER_GCC_OPTIMIZATION_LEVEL_$(CONFIGURATION));
 WK_SANITIZER_GCC_OPTIMIZATION_LEVEL_Debug = 0;
 WK_SANITIZER_GCC_OPTIMIZATION_LEVEL_Production = 1;
@@ -64,11 +66,17 @@ WK_ANY_SANITIZER_LDFLAGS_YES = -Wl,-rpath,@executable_path/Frameworks;
 // Address Sanitizer
 
 // Add -fsanitize-address-use-after-return=never to disable ASan's "fake stack" to fix JSC garbage collection.
-WK_ADDRESS_SANITIZER_OTHER_CFLAGS_YES = -fsanitize-address-use-after-return=never;
+WK_ADDRESS_SANITIZER_OTHER_CFLAGS_YES = -fsanitize-address-use-after-return=never $(WK_WORKAROUND_RDAR_145268301_ASAN_STACK_USE_AFTER_SCOPE);
 WK_ADDRESS_SANITIZER_OTHER_LDFLAGS_YES = -fsanitize-address-use-after-return=never;
 
 WK_ADDRESS_SANITIZER_OTHER_CPLUSPLUSFLAGS_YES = -U_LIBCPP_HAS_NO_ASAN;
 
+// Workaround ASan stack-use-after-scope false positive in Xcode 16.3: <https://bugs.webkit.org/show_bug.cgi?id=288308>.
+WK_NEEDS_RDAR_145268301_ASAN_STACK_USE_AFTER_SCOPE_WORKAROUND = $(WK_NOT_$(WK_XCODE_BEFORE_16_3));
+
+WK_WORKAROUND_RDAR_145268301_ASAN_STACK_USE_AFTER_SCOPE = $(WK_WORKAROUND_RDAR_145268301_ASAN_STACK_USE_AFTER_SCOPE_$(WK_NEEDS_RDAR_145268301_ASAN_STACK_USE_AFTER_SCOPE_WORKAROUND);
+WK_WORKAROUND_RDAR_145268301_ASAN_STACK_USE_AFTER_SCOPE_YES = -DWK_WORKAROUND_RDAR_145268301_ASAN_STACK_USE_AFTER_SCOPE;
+
 // Undefined Behavior Sanitizer
 
 // FIXME: <rdar://105760852> Tune list of Undefined Behavior (UBSan) checkers
diff --git a/Configurations/WebKitTargetConditionals.xcconfig b/Configurations/WebKitTargetConditionals.xcconfig
index e7fba47e5a479..b8f7885e8067d 100644
--- a/Configurations/WebKitTargetConditionals.xcconfig
+++ b/Configurations/WebKitTargetConditionals.xcconfig
@@ -1,4 +1,4 @@
-// Copyright (C) 2018-2024 Apple Inc. All rights reserved.
+// Copyright (C) 2018-2025 Apple Inc. All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions
@@ -380,3 +380,14 @@ WK_XCODE_BEFORE_16_1500 = YES;
 WK_XCODE_16 = $(WK_XCODE_16_$(WK_XCODE_BEFORE_16));
 WK_XCODE_16_ = _XCODE_SINCE_16;
 WK_XCODE_16_YES = _XCODE_BEFORE_16;
+
+WK_XCODE_BEFORE_16_3 = $(WK_XCODE_BEFORE_16_3$(WK_XCODE_16));
+WK_XCODE_BEFORE_16_3_XCODE_BEFORE_16 = YES;
+WK_XCODE_BEFORE_16_3_XCODE_SINCE_16 = $(WK_XCODE_BEFORE_16_3_$(XCODE_VERSION_MINOR));
+WK_XCODE_BEFORE_16_3_1600 = YES;
+WK_XCODE_BEFORE_16_3_1610 = YES;
+WK_XCODE_BEFORE_16_3_1620 = YES;
+
+WK_XCODE_16_3 = $(WK_XCODE_16_3_$(WK_XCODE_BEFORE_16_3));
+WK_XCODE_16_3_ = _XCODE_SINCE_16_3;
+WK_XCODE_16_3_YES = _XCODE_BEFORE_16_3;
diff --git a/Source/ThirdParty/ANGLE/src/compiler/translator/InfoSink.h b/Source/ThirdParty/ANGLE/src/compiler/translator/InfoSink.h
index 8d3b1c0cf16e7..680e5cbb38886 100644
--- a/Source/ThirdParty/ANGLE/src/compiler/translator/InfoSink.h
+++ b/Source/ThirdParty/ANGLE/src/compiler/translator/InfoSink.h
@@ -21,6 +21,9 @@ class TSymbol;
 class TType;
 
 // Returns the fractional part of the given floating-point number.
+#ifdef WK_WORKAROUND_RDAR_145268301_ASAN_STACK_USE_AFTER_SCOPE
+__attribute__((no_sanitize_address))
+#endif
 inline float fractionalPart(float f)
 {
     float intPart = 0.0f;