diff --git a/pycheribuild/config/compilation_targets.py b/pycheribuild/config/compilation_targets.py
index 99d5f8e75..0b8e073e9 100644
--- a/pycheribuild/config/compilation_targets.py
+++ b/pycheribuild/config/compilation_targets.py
@@ -51,6 +51,8 @@
     DefaultInstallDir,
     MipsFloatAbi,
     TargetInfo,
+    cheribsd_morello_version_dependent_flags,
+    sys_param_h_cheribsd_version,
 )
 from ..processutils import extract_version, get_compiler_info, get_version_output
 from ..projects.simple_project import SimpleProject
@@ -689,16 +691,7 @@ def _get_rootfs_class(self, xtarget: "CrossCompileTarget") -> "type[SimpleProjec
         return SimpleProject.get_class_for_target_name("cheribsd", xtarget)
 
     def cheribsd_version(self) -> "Optional[int]":
-        pattern = re.compile(r"#define\s+__CheriBSD_version\s+([0-9]+)")
-        try:
-            with open(self.sysroot_dir / "usr/include/sys/param.h", encoding="utf-8") as f:
-                for line in f:
-                    match = pattern.match(line)
-                    if match:
-                        return int(match.groups()[0])
-        except FileNotFoundError:
-            return None
-        return 0
+        return sys_param_h_cheribsd_version(self.sysroot_dir)
 
 
 class CheriBSDMorelloTargetInfo(CheriBSDTargetInfo):
@@ -729,19 +722,7 @@ def get_non_rootfs_sysroot_dir(self) -> Path:
     def essential_compiler_and_linker_flags_impl(cls, instance: "CheriBSDTargetInfo", *args, xtarget, **kwargs):
         result = super().essential_compiler_and_linker_flags_impl(instance, *args, xtarget=xtarget, **kwargs)
         version = instance.cheribsd_version()
-        # NB: If version is None, no CheriBSD tree exists, so we assume the new
-        # ABI will be used when CheriBSD is eventually built. This ensures the
-        # LLVM config files for the SDK utilities get the right flags in the
-        # common case as otherwise there is a circular dependency.
-        if version is None or version >= 20220511:
-            # Use new var-args ABI
-            result.extend(["-Xclang", "-morello-vararg=new"])
-        if version is None or version >= 20230804:
-            # Use new function call ABI
-            result.extend(["-Xclang", "-morello-bounded-memargs=caller-only"])
-        if xtarget.is_cheri_purecap([CPUArchitecture.AARCH64]) and version is not None and version < 20220511:
-            # Use emulated TLS on older purecap
-            result.append("-femulated-tls")
+        result.extend(cheribsd_morello_version_dependent_flags(version, xtarget.is_cheri_purecap()))
         return result
 
 
diff --git a/pycheribuild/config/target_info.py b/pycheribuild/config/target_info.py
index 1e57561a0..9aeca978d 100644
--- a/pycheribuild/config/target_info.py
+++ b/pycheribuild/config/target_info.py
@@ -29,6 +29,7 @@
 #
 import functools
 import platform
+import re
 import typing
 from abc import ABC, abstractmethod
 from enum import Enum
@@ -52,6 +53,8 @@
     "MipsFloatAbi",
     "NativeTargetInfo",
     "TargetInfo",
+    "sys_param_h_cheribsd_version",
+    "cheribsd_morello_version_dependent_flags",
 ]
 
 
@@ -742,11 +745,18 @@ def essential_compiler_and_linker_flags_impl(
                 instance.project.fatal(
                     "Requested automatic variable initialization, but don't know how to for", compiler
                 )
-        if xtarget.is_cheri_hybrid():
+        if cls.is_cheribsd():
             if xtarget.is_aarch64(include_purecap=True):
-                result.append("-mabi=aapcs")
+                cheribsd_version = sys_param_h_cheribsd_version(Path("/"))
+                result.extend(cheribsd_morello_version_dependent_flags(cheribsd_version, xtarget.is_cheri_purecap()))
+                if xtarget.is_cheri_purecap():
+                    result.append("-mabi=purecap")
+                else:
+                    assert xtarget.is_cheri_hybrid(), "non-cheri not supported"
+                    result.append("-mabi=aapcs")  # in case cc defaults to -mabi=purecap
+                result.append("-mcpu=rainier")
             else:
-                instance.project.fatal("-native-hybrid not supported yet for non-Morello targets")
+                instance.project.fatal("Native CheriBSD compilation currently only supported for Morello targets")
         return result  # default host compiler should not need any extra flags
 
 
@@ -1111,6 +1121,38 @@ def _is_native_purecap():
     return OSInfo.is_cheribsd() and platform.processor() in ("aarch64c", "riscv64c")
 
 
+@functools.lru_cache(maxsize=3)
+def sys_param_h_cheribsd_version(sysroot: Path) -> "Optional[int]":
+    pattern = re.compile(r"#define\s+__CheriBSD_version\s+([0-9]+)")
+    try:
+        with open(sysroot / "usr/include/sys/param.h", encoding="utf-8") as f:
+            for line in f:
+                match = pattern.match(line)
+                if match:
+                    return int(match.groups()[0])
+    except FileNotFoundError:
+        return None
+    return 0
+
+
+def cheribsd_morello_version_dependent_flags(cheribsd_version: "Optional[int]", is_purecap) -> "list[str]":
+    result = []
+    # NB: If version is None, no CheriBSD tree exists, so we assume the new
+    # ABI will be used when CheriBSD is eventually built. This ensures the
+    # LLVM config files for the SDK utilities get the right flags in the
+    # common case as otherwise there is a circular dependency.
+    if cheribsd_version is None or cheribsd_version >= 20220511:
+        # Use new var-args ABI
+        result.extend(["-Xclang", "-morello-vararg=new"])
+    if cheribsd_version is None or cheribsd_version >= 20230804:
+        # Use new function call ABI
+        result.extend(["-Xclang", "-morello-bounded-memargs=caller-only"])
+    if is_purecap and cheribsd_version is not None and cheribsd_version < 20220511:
+        # Use emulated TLS on older purecap
+        result.append("-femulated-tls")
+    return result
+
+
 # This is a separate class to avoid cyclic dependencies.
 # The real list is in CompilationTargets in compilation_targets.py
 class BasicCompilationTargets: