diff --git a/llvm/lib/Target/AArch64/AArch64CallingConvention.h b/llvm/lib/Target/AArch64/AArch64CallingConvention.h
--- a/llvm/lib/Target/AArch64/AArch64CallingConvention.h
+++ b/llvm/lib/Target/AArch64/AArch64CallingConvention.h
@@ -43,6 +43,9 @@
 bool CC_AArch64_Win64_CFGuard_Check(unsigned ValNo, MVT ValVT, MVT LocVT,
                                     CCValAssign::LocInfo LocInfo,
                                     ISD::ArgFlagsTy ArgFlags, CCState &State);
+bool CC_AArch64_Arm64EC_CFGuard_Check(unsigned ValNo, MVT ValVT, MVT LocVT,
+                                      CCValAssign::LocInfo LocInfo,
+                                      ISD::ArgFlagsTy ArgFlags, CCState &State);
 bool CC_AArch64_WebKit_JS(unsigned ValNo, MVT ValVT, MVT LocVT,
                           CCValAssign::LocInfo LocInfo,
                           ISD::ArgFlagsTy ArgFlags, CCState &State);
@@ -55,6 +58,10 @@
 bool RetCC_AArch64_Arm64EC_Thunk(unsigned ValNo, MVT ValVT, MVT LocVT,
                                  CCValAssign::LocInfo LocInfo,
                                  ISD::ArgFlagsTy ArgFlags, CCState &State);
+bool RetCC_AArch64_Arm64EC_CFGuard_Check(unsigned ValNo, MVT ValVT, MVT LocVT,
+                                         CCValAssign::LocInfo LocInfo,
+                                         ISD::ArgFlagsTy ArgFlags,
+                                         CCState &State);
 bool RetCC_AArch64_WebKit_JS(unsigned ValNo, MVT ValVT, MVT LocVT,
                              CCValAssign::LocInfo LocInfo,
                              ISD::ArgFlagsTy ArgFlags, CCState &State);
diff --git a/llvm/lib/Target/AArch64/AArch64CallingConvention.td b/llvm/lib/Target/AArch64/AArch64CallingConvention.td
--- a/llvm/lib/Target/AArch64/AArch64CallingConvention.td
+++ b/llvm/lib/Target/AArch64/AArch64CallingConvention.td
@@ -327,6 +327,16 @@
   CCIfType<[i64], CCAssignToReg<[X15]>>
 ]>;
 
+let Entry = 1 in
+def CC_AArch64_Arm64EC_CFGuard_Check : CallingConv<[
+  CCIfType<[i64], CCAssignToReg<[X11, X10]>>
+]>;
+
+let Entry = 1 in
+def RetCC_AArch64_Arm64EC_CFGuard_Check : CallingConv<[
+  CCIfType<[i64], CCAssignToReg<[X11]>>
+]>;
+
 
 // Darwin uses a calling convention which differs in only two ways
 // from the standard one at this level:
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -5829,6 +5829,8 @@
     }
     return CC_AArch64_AAPCS;
   case CallingConv::CFGuard_Check:
+    if (Subtarget->isWindowsArm64EC())
+      return CC_AArch64_Arm64EC_CFGuard_Check;
     return CC_AArch64_Win64_CFGuard_Check;
   case CallingConv::AArch64_VectorCall:
   case CallingConv::AArch64_SVE_VectorCall:
@@ -5849,6 +5851,10 @@
     return RetCC_AArch64_WebKit_JS;
   case CallingConv::ARM64EC_Thunk_X64:
     return RetCC_AArch64_Arm64EC_Thunk;
+  case CallingConv::CFGuard_Check:
+    if (Subtarget->isWindowsArm64EC())
+      return RetCC_AArch64_Arm64EC_CFGuard_Check;
+    return RetCC_AArch64_AAPCS;
   }
 }