diff --git a/README.md b/README.md
index 89057cddec..7b42600eaa 100644
--- a/README.md
+++ b/README.md
@@ -129,7 +129,7 @@ then build and install USD into `/path/to/my_usd_install_dir`.
 > python USD/build_scripts/build_usd.py /path/to/my_usd_install_dir
 ```
 
-##### MacOS:
+##### macOS:
 
 In a terminal, run `xcode-select` to ensure command line developer tools are
 installed. Then run the script.
@@ -141,6 +141,14 @@ then build and install USD into `/path/to/my_usd_install_dir`.
 > python USD/build_scripts/build_usd.py /path/to/my_usd_install_dir
 ```
 
+###### iOS
+
+When building from a macOS system, you can also cross compile for other iOS.
+To build for iOS, add the `--build-target iOS` parameter.
+
+iOS builds currently do not support Imaging.
+Additionally, they will not support Python bindings or command line tools.
+
 ##### Windows:
 
 Launch the "x64 Native Tools Command Prompt" for your version of Visual Studio
diff --git a/build_scripts/apple_utils.py b/build_scripts/apple_utils.py
index 2c82243896..8c5263502d 100644
--- a/build_scripts/apple_utils.py
+++ b/build_scripts/apple_utils.py
@@ -35,20 +35,26 @@
 import platform
 import shlex
 import subprocess
+import re
+from typing import Optional, List
 
 TARGET_NATIVE = "native"
 TARGET_X86 = "x86_64"
 TARGET_ARM64 = "arm64"
 TARGET_UNIVERSAL = "universal"
+TARGET_IOS = "ios"
+
+EMBEDDED_PLATFORMS = [TARGET_IOS]
 
 def GetBuildTargets():
     return [TARGET_NATIVE,
             TARGET_X86,
             TARGET_ARM64,
-            TARGET_UNIVERSAL]
+            TARGET_UNIVERSAL,
+            TARGET_IOS]
 
 def GetBuildTargetDefault():
-    return TARGET_NATIVE;
+    return TARGET_NATIVE
 
 def MacOS():
     return platform.system() == "Darwin"
@@ -56,15 +62,11 @@ def MacOS():
 def GetLocale():
     return sys.stdout.encoding or locale.getdefaultlocale()[1] or "UTF-8"
 
-def GetCommandOutput(command):
-    """Executes the specified command and returns output or None."""
+def GetCommandOutput(command, **kwargs):
     try:
-        return subprocess.check_output(
-            shlex.split(command),
-            stderr=subprocess.STDOUT).decode(GetLocale(), 'replace').strip()
-    except subprocess.CalledProcessError:
-        pass
-    return None
+        return subprocess.check_output(command, stderr=subprocess.STDOUT, **kwargs).decode(GetLocale(), 'replace').strip()
+    except:
+        return None
 
 def GetTargetArmArch():
     # Allows the arm architecture string to be overridden by
@@ -72,7 +74,7 @@ def GetTargetArmArch():
     return os.environ.get('MACOS_ARM_ARCHITECTURE') or TARGET_ARM64
 
 def GetHostArch():
-    macArch = GetCommandOutput('arch').strip()
+    macArch = GetCommandOutput(["arch"])
     if macArch == "i386" or macArch == TARGET_X86:
         macArch = TARGET_X86
     else:
@@ -85,7 +87,7 @@ def GetTargetArch(context):
     else:
         if context.targetX86:
             macTargets = TARGET_X86
-        if context.targetARM64:
+        if context.targetARM64 or context.targetIos:
             macTargets = GetTargetArmArch()
         if context.targetUniversal:
             macTargets = TARGET_X86 + ";" + GetTargetArmArch()
@@ -106,6 +108,8 @@ def GetTargetArchPair(context):
         primaryArch = TARGET_X86
     if context.targetARM64:
         primaryArch = GetTargetArmArch()
+    if context.targetIos:
+        primaryArch = TARGET_IOS
     if context.targetUniversal:
         primaryArch = GetHostArch()
         if (primaryArch == TARGET_X86):
@@ -118,18 +122,52 @@ def GetTargetArchPair(context):
 def SupportsMacOSUniversalBinaries():
     if not MacOS():
         return False
-    XcodeOutput = GetCommandOutput('/usr/bin/xcodebuild -version')
+    XcodeOutput = GetCommandOutput(["/usr/bin/xcodebuild", "-version"])
     XcodeFind = XcodeOutput.rfind('Xcode ', 0, len(XcodeOutput))
     XcodeVersion = XcodeOutput[XcodeFind:].split(' ')[1]
     return (XcodeVersion > '11.0')
 
+
+def GetSDKVersion(sdk: str) -> Optional[str]:
+    """Gets the SDK version from the currently active Xcode"""
+    sdks = GetCommandOutput(["xcodebuild", "-showsdks"]).split(os.linesep)
+    for line in sdks:
+        line = line.strip()
+        if sdk not in line or "-sdk" not in line:
+            continue
+
+        line = line.split("-sdk ")[-1]
+        if not line.startswith(sdk):
+            continue
+
+        tokens = [t for t in line.replace(sdk, "").split(".") if t.isnumeric()]
+        if not tokens:
+            continue
+        return ".".join(tokens)
+    return None
+
+def GetSDKRoot(context) -> Optional[str]:
+    sdk = "macosx"
+    if context.buildTarget == TARGET_IOS:
+        sdk = "iphoneos"
+
+    for arg in (context.cmakeBuildArgs or '').split():
+        if "CMAKE_OSX_SYSROOT" in arg:
+            override = arg.split('=')[1].strip('"').strip()
+            if override:
+                sdk = override
+    return GetCommandOutput(["xcrun", "--sdk", sdk, "--show-sdk-path"])
+
+
 def SetTarget(context, targetName):
     context.targetNative = (targetName == TARGET_NATIVE)
     context.targetX86 = (targetName == TARGET_X86)
     context.targetARM64 = (targetName == GetTargetArmArch())
     context.targetUniversal = (targetName == TARGET_UNIVERSAL)
+    context.targetIos = (targetName == TARGET_IOS)
+    context.iosVersion = GetSDKVersion("iphoneos") if context.targetIos else None
     if context.targetUniversal and not SupportsMacOSUniversalBinaries():
-        self.targetUniversal = False
+        context.targetUniversal = False
         raise ValueError(
                 "Universal binaries only supported in macOS 11.0 and later.")
 
@@ -150,26 +188,63 @@ def ExtractFilesRecursive(path, cond):
                 files.append(os.path.join(r, file))
     return files
 
-def CodesignFiles(files):
-    SDKVersion  = subprocess.check_output(
-        ['xcodebuild', '-version']).strip()[6:10]
-    codeSignIDs = subprocess.check_output(
-        ['security', 'find-identity', '-vp', 'codesigning'])
+def _GetCodeSignStringFromTerminal():
+    codeSignIDs = GetCommandOutput(['security', 'find-identity', '-vp', 'codesigning'])
+    return codeSignIDs
 
-    codeSignID = "-"
+def GetCodeSignID():
     if os.environ.get('CODE_SIGN_ID'):
-        codeSignID = os.environ.get('CODE_SIGN_ID')
-    elif float(SDKVersion) >= 11.0 and \
-                codeSignIDs.find(b'Apple Development') != -1:
-        codeSignID = "Apple Development"
-    elif codeSignIDs.find(b'Mac Developer') != -1:
-        codeSignID = "Mac Developer"
+        return os.environ.get('CODE_SIGN_ID')
+
+    codeSignIDs = _GetCodeSignStringFromTerminal()
+    if not codeSignIDs:
+        return "-"
+    for codeSignID in codeSignIDs.splitlines():
+        if "CSSMERR_TP_CERT_REVOKED" in codeSignID:
+            continue
+        if ")" not in codeSignID:
+            continue
+        codeSignID = codeSignID.split()[1]
+        break
+    else:
+        raise RuntimeError("Could not find a valid codesigning ID")
+
+    return codeSignID or "-"
+
+def GetCodeSignIDHash():
+    codeSignIDs = _GetCodeSignStringFromTerminal()
+    try:
+        return re.findall(r'\(.*?\)', codeSignIDs)[0][1:-1]
+    except:
+        raise Exception("Unable to parse codesign ID hash")
+
+def GetDevelopmentTeamID():
+    if os.environ.get("DEVELOPMENT_TEAM"):
+        return os.environ.get("DEVELOPMENT_TEAM")
+    codesignID = GetCodeSignIDHash()
+
+    certs = subprocess.check_output(["security", "find-certificate", "-c", codesignID, "-p"])
+    subject = GetCommandOutput(["openssl", "x509", "-subject"], input=certs)
+    subject = subject.splitlines()[0]
+
+    # Extract the Organizational Unit (OU field) from the cert
+    try:
+        team = [elm for elm in subject.split(
+            '/') if elm.startswith('OU')][0].split('=')[1]
+        if team is not None and team != "":
+            return team
+    except Exception as ex:
+        raise Exception("No development team found with exception " + ex)
+
+def CodesignFiles(files):
+    codeSignID = GetCodeSignID()
 
     for f in files:
         subprocess.call(['codesign', '-f', '-s', '{codesignid}'
-                              .format(codesignid=codeSignID), f],
+                        .format(codesignid=codeSignID), f],
                         stdout=devout, stderr=devout)
 
+
 def Codesign(install_path, verbose_output=False):
     if not MacOS():
         return False
@@ -217,3 +292,12 @@ def CreateUniversalBinaries(context, libNames, x86Dir, armDir):
                                 instDir=context.instDir, libName=targetName),
                        outputName)
     return lipoCommands
+
+def ConfigureCMakeExtraArgs(context, args:List[str]) -> List[str]:
+    system_name = None
+    if context.buildTarget == TARGET_IOS:
+        system_name = "iOS"
+
+    if system_name:
+        args.append(f"-DCMAKE_SYSTEM_NAME={system_name}")
+    return args
\ No newline at end of file
diff --git a/build_scripts/build_usd.py b/build_scripts/build_usd.py
index 5c47ab5547..aeea1aa6ca 100644
--- a/build_scripts/build_usd.py
+++ b/build_scripts/build_usd.py
@@ -51,6 +51,7 @@
 
 from urllib.request import urlopen
 from shutil import which
+import apple_utils
 
 # Helpers for printing output
 verbosity = 1
@@ -89,9 +90,6 @@ def Linux():
 def MacOS():
     return platform.system() == "Darwin"
 
-if MacOS():
-    import apple_utils
-
 def GetLocale():
     if Windows():
         # Windows handles encoding a little differently then Linux / Mac
@@ -251,7 +249,7 @@ def GetCPUCount():
     except NotImplementedError:
         return 1
 
-def Run(cmd, logCommandOutput = True):
+def Run(cmd, logCommandOutput = True, env=None):
     """Run the specified command in a subprocess."""
     PrintInfo('Running "{cmd}"'.format(cmd=cmd))
 
@@ -265,7 +263,7 @@ def Run(cmd, logCommandOutput = True):
         # code will handle them.
         if logCommandOutput:
             p = subprocess.Popen(shlex.split(cmd), stdout=subprocess.PIPE, 
-                                 stderr=subprocess.STDOUT)
+                                 stderr=subprocess.STDOUT, env=env)
             while True:
                 l = p.stdout.readline().decode(GetLocale(), 'replace')
                 if l:
@@ -274,7 +272,7 @@ def Run(cmd, logCommandOutput = True):
                 elif p.poll() is not None:
                     break
         else:
-            p = subprocess.Popen(shlex.split(cmd))
+            p = subprocess.Popen(shlex.split(cmd), env=env)
             p.wait()
 
     if p.returncode != 0:
@@ -420,6 +418,7 @@ def RunCMake(context, force, extraArgs = None):
             extraArgs.append('-DCMAKE_XCODE_ATTRIBUTE_ONLY_ACTIVE_ARCH=NO')
 
         extraArgs.append('-DCMAKE_OSX_ARCHITECTURES={0}'.format(targetArch))
+        extraArgs = apple_utils.ConfigureCMakeExtraArgs(context, extraArgs)
 
     if context.ignorePaths:
         ignoredPaths = ";".join(context.ignorePaths)
@@ -689,6 +688,19 @@ def AnyPythonDependencies(deps):
 
 def InstallZlib(context, force, buildArgs):
     with CurrentWorkingDirectory(DownloadURL(ZLIB_URL, context, force)):
+        # The following test files aren't portable to embedded platforms.
+        # They're not required for use on any platforms, so we elide them for efficiency
+        PatchFile("CMakeLists.txt",
+                  [("add_executable(example test/example.c)",
+                    ""),
+                   ("add_executable(minigzip test/minigzip.c)",
+                    ""),
+                   ("target_link_libraries(example zlib)",
+                    ""),
+                   ("target_link_libraries(minigzip zlib)",
+                    ""),
+                   ("add_test(example example)",
+                    "")])
         RunCMake(context, force, buildArgs)
 
 ZLIB = Dependency("zlib", InstallZlib, "include/zlib.h")
@@ -996,15 +1008,31 @@ def InstallTBB_MacOS(context, force, buildArgs):
         if (secondaryArch == apple_utils.TARGET_X86):
             secondaryArch = "intel64"
 
+        # fixup if condition in main make config
+        PatchFile("build/macos.clang.inc",
+                  [("TARGET)\nelse\n", "TARGET)\nelse ifeq (macos,$(target))\n")],
+                  multiLineMatches=True)
+
+        if context.buildTarget == apple_utils.TARGET_IOS:
+            primaryArch = "arm64"
+            buildArgs.append('compiler=clang arch=arm64 extra_inc=big_iron.inc ')
+
         # Install both release and debug builds.
         # See comments in InstallTBB_Linux.
         def _RunBuild(arch):
             if not arch:
                 return
-            makeTBBCmd = 'make -j{procs} arch={arch} {buildArgs}'.format(
+            platformArg = ""
+            env = os.environ.copy()
+            if context.buildTarget == apple_utils.TARGET_IOS:
+                platformArg = "target=ios"
+                env["SDKROOT"] = apple_utils.GetSDKRoot(context)
+            makeTBBCmd = 'make -j{procs} arch={arch} {platformArg} {buildArgs}'.format(
                 arch=arch, procs=context.numJobs,
+                platformArg = platformArg,
                 buildArgs=" ".join(buildArgs))
-            Run(makeTBBCmd)
+
+            Run(makeTBBCmd, env=env)
 
         _RunBuild(primaryArch)
         _RunBuild(secondaryArch)
@@ -1356,6 +1384,9 @@ def InstallOpenSubdiv(context, force, buildArgs):
             '-DNO_GLFW=ON',
         ]
 
+        if MacOS():
+            extraArgs.append('-DNO_OPENGL=ON')
+
         # If Ptex support is disabled in USD, disable support in OpenSubdiv
         # as well. This ensures OSD doesn't accidentally pick up a Ptex
         # library outside of our build.
@@ -1491,7 +1522,7 @@ def InstallDraco(context, force, buildArgs):
 ############################################################
 # MaterialX
 
-MATERIALX_URL = "https://github.com/materialx/MaterialX/archive/v1.38.7.zip"
+MATERIALX_URL = "https://github.com/materialx/MaterialX/archive/v1.38.8.zip"
 
 def InstallMaterialX(context, force, buildArgs):
     with CurrentWorkingDirectory(DownloadURL(MATERIALX_URL, context, force)):
@@ -1507,6 +1538,12 @@ def InstallMaterialX(context, force, buildArgs):
         cmakeOptions = ['-DMATERIALX_BUILD_SHARED_LIBS=ON',
                         '-DMATERIALX_BUILD_TESTS=OFF'
         ]
+        if context.buildTarget in apple_utils.EMBEDDED_PLATFORMS:
+            cmakeOptions.extend([
+                "-DMATERIALX_BUILD_GEN_MSL=ON",
+                "-DMATERIALX_BUILD_GEN_GLSL=OFF",
+                "-DMATERIALX_BUILD_IOS=ON"
+            ])
         cmakeOptions += buildArgs
         RunCMake(context, force, cmakeOptions)
 
@@ -1747,6 +1784,13 @@ def InstallUSD(context, force, buildArgs):
             # Increase the precompiled header buffer limit.
             extraArgs.append('-DCMAKE_CXX_FLAGS="/Zm150"')
 
+        if context.buildTarget in apple_utils.EMBEDDED_PLATFORMS:
+            # Required to find locally built boost etc.
+            extraArgs.extend([
+                '-DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=BOTH',
+                '-DCMAKE_FIND_ROOT_PATH_MODE_INCLUDE=BOTH',
+                '-DCMAKE_FIND_ROOT_PATH_MODE_LIBRARY=BOTH'])
+
         # Make sure to use boost installed by the build script and not any
         # system installed boost
         extraArgs.append('-DBoost_NO_BOOST_CMAKE=On')
@@ -2172,6 +2216,8 @@ def __init__(self, args):
         self.buildMonolithic = (args.build_type == MONOLITHIC_LIB)
 
         self.ignorePaths = args.ignore_paths or []
+        self.buildTarget = None
+        self.macOSCodesign = ""
         # Build target and code signing
         if MacOS():
             self.buildTarget = args.build_target
@@ -2182,8 +2228,8 @@ def __init__(self, args):
                  else False)
             if apple_utils.IsHostArm() and args.ignore_homebrew:
                 self.ignorePaths.append("/opt/homebrew")
-        else:
-            self.buildTarget = ""
+
+        coreOnly = self.buildTarget in apple_utils.EMBEDDED_PLATFORMS
 
         self.useCXX11ABI = \
             (args.use_cxx11_abi if hasattr(args, "use_cxx11_abi") else None)
@@ -2195,10 +2241,10 @@ def __init__(self, args):
 
         # Optional components
         self.buildTests = args.build_tests
-        self.buildPython = args.build_python
+        self.buildPython = args.build_python and not coreOnly
         self.buildExamples = args.build_examples
         self.buildTutorials = args.build_tutorials
-        self.buildTools = args.build_tools
+        self.buildTools = args.build_tools and not coreOnly
 
         # - Documentation
         self.buildDocs = args.build_docs or args.build_python_docs
@@ -2207,7 +2253,7 @@ def __init__(self, args):
 
         # - Imaging
         self.buildImaging = (args.build_imaging == IMAGING or
-                             args.build_imaging == USD_IMAGING)
+                             args.build_imaging == USD_IMAGING) and not coreOnly
         self.enablePtex = self.buildImaging and args.enable_ptex
         self.enableOpenVDB = self.buildImaging and args.enable_openvdb
 
@@ -2634,8 +2680,11 @@ def FormatBuildArguments(buildArgs):
     if context.macOSCodesign:
         apple_utils.Codesign(context.usdInstDir, verbosity > 1)
 
-Print("""
-Success! To use USD, please ensure that you have:""")
+printInstructions = any([context.buildPython, context.buildTools, context.buildPrman])
+if printInstructions:
+    Print("\nSuccess! To use USD, please ensure that you have:")
+else:
+    Print("\nSuccess! USD libraries were built.")
 
 if context.buildPython:
     Print("""
@@ -2643,10 +2692,11 @@ def FormatBuildArguments(buildArgs):
     {requiredInPythonPath}""".format(
         requiredInPythonPath="\n    ".join(sorted(requiredInPythonPath))))
 
-Print("""
-    The following in your PATH environment variable:
-    {requiredInPath}
-""".format(requiredInPath="\n    ".join(sorted(requiredInPath))))
+if context.buildTools:
+    Print("""
+        The following in your PATH environment variable:
+        {requiredInPath}
+    """.format(requiredInPath="\n    ".join(sorted(requiredInPath))))
     
 if context.buildPrman:
     Print("See documentation at http://openusd.org/docs/RenderMan-USD-Imaging-Plugin.html "
diff --git a/pxr/base/arch/align.cpp b/pxr/base/arch/align.cpp
index 5ec8a8e65b..8e1aa4029c 100644
--- a/pxr/base/arch/align.cpp
+++ b/pxr/base/arch/align.cpp
@@ -26,11 +26,12 @@
 #include "pxr/base/arch/defines.h"
 #include "pxr/base/arch/error.h"
 
-#if defined(ARCH_OS_DARWIN)
+#if defined(ARCH_OS_IPHONE)
+#elif defined(ARCH_OS_DARWIN)
 #   include <sys/malloc.h>
 #else
 #   include <malloc.h>
-#endif /* defined(ARCH_OS_DARWIN) */
+#endif /* defined(ARCH_OS_IPHONE) */
 
 #include <cstdlib>
 
diff --git a/pxr/base/arch/debugger.cpp b/pxr/base/arch/debugger.cpp
index fd093f09e9..4039d0d57e 100644
--- a/pxr/base/arch/debugger.cpp
+++ b/pxr/base/arch/debugger.cpp
@@ -34,7 +34,9 @@
 #if defined(ARCH_OS_LINUX) || defined(ARCH_OS_DARWIN)
 #include "pxr/base/arch/inttypes.h"
 #include <sys/types.h>
+#if !defined(ARCH_OS_IPHONE)
 #include <sys/ptrace.h>
+#endif
 #include <sys/stat.h>
 #include <sys/wait.h>
 #include <cstdio>
diff --git a/pxr/base/arch/defines.h b/pxr/base/arch/defines.h
index cb6ad44c5b..b5c10f88b5 100644
--- a/pxr/base/arch/defines.h
+++ b/pxr/base/arch/defines.h
@@ -34,7 +34,10 @@
 #include "TargetConditionals.h"
 #define ARCH_OS_DARWIN
 #if TARGET_OS_IPHONE
-#define ARCH_OS_IOS
+// TARGET_OS_IPHONE refers to all iOS derivative platforms
+// TARGET_OS_IOS refers to iPhone/iPad
+// For now, we only specialize for the umbrella TARGET_OS_IPHONE group
+#define ARCH_OS_IPHONE
 #else
 #define ARCH_OS_OSX
 #endif
diff --git a/pxr/base/arch/mallocHook.cpp b/pxr/base/arch/mallocHook.cpp
index e47787d7a6..cf776feb8a 100644
--- a/pxr/base/arch/mallocHook.cpp
+++ b/pxr/base/arch/mallocHook.cpp
@@ -33,11 +33,12 @@
 #endif
 #include <cstring>
 
-#if defined(ARCH_OS_DARWIN)
+#if defined(ARCH_OS_IPHONE)
+#elif defined(ARCH_OS_DARWIN)
 #   include <sys/malloc.h>
 #else
 #   include <malloc.h>
-#endif /* defined(ARCH_OS_DARWIN) */
+#endif /* defined(ARCH_OS_IPHONE) */
 
 PXR_NAMESPACE_OPEN_SCOPE
 
diff --git a/pxr/imaging/garch/glPlatformContextDarwin.mm b/pxr/imaging/garch/glPlatformContextDarwin.mm
index fccfa3b81b..950663319f 100644
--- a/pxr/imaging/garch/glPlatformContextDarwin.mm
+++ b/pxr/imaging/garch/glPlatformContextDarwin.mm
@@ -27,7 +27,7 @@
 #include "pxr/pxr.h"
 #include "glPlatformContextDarwin.h"
 
-#ifdef ARCH_OS_IOS
+#ifdef ARCH_OS_IPHONE
 typedef EAGLContext NSGLContext;
 #else
 typedef NSOpenGLContext NSGLContext;
@@ -90,7 +90,7 @@
 void
 GarchNSGLContextState::MakeCurrent()
 {
-#if ARCH_OS_IOS
+#if ARCH_OS_IPHONE
     [EAGLContext setCurrentContext:_detail->context];
 #else
     [_detail->context makeCurrentContext];
diff --git a/pxr/imaging/hgiMetal/capabilities.mm b/pxr/imaging/hgiMetal/capabilities.mm
index 7d8065bd19..20aedef37a 100644
--- a/pxr/imaging/hgiMetal/capabilities.mm
+++ b/pxr/imaging/hgiMetal/capabilities.mm
@@ -50,7 +50,7 @@
     if (@available(macOS 100.100, ios 12.0, *)) {
         unifiedMemory = true;
     } else if (@available(macOS 10.15, ios 13.0, *)) {
-#if defined(ARCH_OS_IOS) || (defined(__MAC_10_15) && __MAC_OS_X_VERSION_MAX_ALLOWED >= __MAC_10_15)
+#if defined(ARCH_OS_IPHONE) || (defined(__MAC_10_15) && __MAC_OS_X_VERSION_MAX_ALLOWED >= __MAC_10_15)
         unifiedMemory = [device hasUnifiedMemory];
 #else
         unifiedMemory = [device isLowPower];
diff --git a/pxr/imaging/hgiMetal/shaderGenerator.mm b/pxr/imaging/hgiMetal/shaderGenerator.mm
index 0138b66c15..3a8e252fae 100644
--- a/pxr/imaging/hgiMetal/shaderGenerator.mm
+++ b/pxr/imaging/hgiMetal/shaderGenerator.mm
@@ -375,7 +375,7 @@ void _Init(
     }
 
     if (@available(macos 100.100, ios 12.0, *)) {
-        header  << "#define ARCH_OS_IOS\n";
+        header  << "#define ARCH_OS_IPHONE\n";
         // Define all iOS 12 feature set enums onwards
         if ([device supportsFeatureSet:MTLFeatureSet(12)])
             header << "#define METAL_FEATURESET_IOS_GPUFAMILY1_v5\n";
diff --git a/pxr/imaging/hio/stbImage.cpp b/pxr/imaging/hio/stbImage.cpp
index c9a85938a5..9ff197868d 100644
--- a/pxr/imaging/hio/stbImage.cpp
+++ b/pxr/imaging/hio/stbImage.cpp
@@ -439,7 +439,7 @@ Hio_StbImage::ReadCropped(int const cropTop,
     // thus we explicitly call stbi__vertical_flip below - assuming
     // that no other client called stbi_set_flip_vertically_on_load(true).
     
-#if defined(ARCH_OS_IOS)
+#if defined(ARCH_OS_IPHONE)
     stbi_convert_iphone_png_to_rgb(true);
 #endif