diff --git a/ArmPkg/Drivers/ArmGic/ArmGicDxe.h b/ArmPkg/Drivers/ArmGic/ArmGicDxe.h
index bf067ae03e..c78b788ac0 100644
--- a/ArmPkg/Drivers/ArmGic/ArmGicDxe.h
+++ b/ArmPkg/Drivers/ArmGic/ArmGicDxe.h
@@ -6,8 +6,8 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 
 --*/
 
-#ifndef __ARM_GIC_DXE_H__
-#define __ARM_GIC_DXE_H__
+#ifndef ARM_GIC_DXE_H_
+#define ARM_GIC_DXE_H_
 
 #include <Library/ArmGicLib.h>
 #include <Library/ArmLib.h>
@@ -76,4 +76,4 @@ GicGetDistributorIcfgBaseAndBit (
   OUT UINTN                               *Config1Bit
   );
 
-#endif
+#endif // ARM_GIC_DXE_H_
diff --git a/ArmPkg/Drivers/CpuDxe/CpuDxe.h b/ArmPkg/Drivers/CpuDxe/CpuDxe.h
index 3fe5c24d5e..4cf3ab258c 100644
--- a/ArmPkg/Drivers/CpuDxe/CpuDxe.h
+++ b/ArmPkg/Drivers/CpuDxe/CpuDxe.h
@@ -7,8 +7,8 @@
 
 **/
 
-#ifndef __CPU_DXE_ARM_EXCEPTION_H__
-#define __CPU_DXE_ARM_EXCEPTION_H__
+#ifndef CPU_DXE_H_
+#define CPU_DXE_H_
 
 #include <Uefi.h>
 
@@ -143,4 +143,4 @@ SetGcdMemorySpaceAttributes (
   IN UINT64                              Attributes
   );
 
-#endif // __CPU_DXE_ARM_EXCEPTION_H__
+#endif // CPU_DXE_H_
diff --git a/ArmPkg/Drivers/GenericWatchdogDxe/GenericWatchdog.h b/ArmPkg/Drivers/GenericWatchdogDxe/GenericWatchdog.h
index c64bc5c462..28db57e07b 100644
--- a/ArmPkg/Drivers/GenericWatchdogDxe/GenericWatchdog.h
+++ b/ArmPkg/Drivers/GenericWatchdogDxe/GenericWatchdog.h
@@ -5,8 +5,8 @@
 *  SPDX-License-Identifier: BSD-2-Clause-Patent
 *
 **/
-#ifndef __GENERIC_WATCHDOG_H__
-#define __GENERIC_WATCHDOG_H__
+#ifndef GENERIC_WATCHDOG_H_
+#define GENERIC_WATCHDOG_H_
 
 // Refresh Frame:
 #define GENERIC_WDOG_REFRESH_REG              ((UINTN)FixedPcdGet64 (PcdGenericWatchdogRefreshBase) + 0x000)
@@ -21,4 +21,4 @@
 #define GENERIC_WDOG_ENABLED          1
 #define GENERIC_WDOG_DISABLED         0
 
-#endif  // __GENERIC_WATCHDOG_H__
+#endif  // GENERIC_WATCHDOG_H_
diff --git a/ArmPkg/Filesystem/SemihostFs/Arm/SemihostFs.h b/ArmPkg/Filesystem/SemihostFs/Arm/SemihostFs.h
index ce92fe9f1b..5fe7c5f4d4 100644
--- a/ArmPkg/Filesystem/SemihostFs/Arm/SemihostFs.h
+++ b/ArmPkg/Filesystem/SemihostFs/Arm/SemihostFs.h
@@ -7,8 +7,8 @@
 
 **/
 
-#ifndef __SEMIHOST_FS_H__
-#define __SEMIHOST_FS_H__
+#ifndef SEMIHOST_FS_H_
+#define SEMIHOST_FS_H_
 
 EFI_STATUS
 VolumeOpen (
@@ -242,5 +242,5 @@ FileFlush (
   IN EFI_FILE *File
   );
 
-#endif // __SEMIHOST_FS_H__
+#endif // SEMIHOST_FS_H_
 
diff --git a/ArmPkg/Include/AsmMacroIoLib.h b/ArmPkg/Include/AsmMacroIoLib.h
index e3576c8beb..6c901ac387 100644
--- a/ArmPkg/Include/AsmMacroIoLib.h
+++ b/ArmPkg/Include/AsmMacroIoLib.h
@@ -10,8 +10,8 @@
 **/
 
 
-#ifndef __MACRO_IO_LIB_H__
-#define __MACRO_IO_LIB_H__
+#ifndef ASM_MACRO_IO_LIB_H_
+#define ASM_MACRO_IO_LIB_H_
 
 #define _ASM_FUNC(Name, Section)    \
   .global   Name                  ; \
@@ -36,4 +36,4 @@
   movt      Reg, #:upper16:(Sym) - (. + 12) ; \
   ldr       Reg, [pc, Reg]
 
-#endif
+#endif // ASM_MACRO_IO_LIB_H_
diff --git a/ArmPkg/Include/AsmMacroIoLibV8.h b/ArmPkg/Include/AsmMacroIoLibV8.h
index bcc0d8dafe..337d9ae016 100644
--- a/ArmPkg/Include/AsmMacroIoLibV8.h
+++ b/ArmPkg/Include/AsmMacroIoLibV8.h
@@ -10,8 +10,8 @@
 **/
 
 
-#ifndef __MACRO_IO_LIBV8_H__
-#define __MACRO_IO_LIBV8_H__
+#ifndef ASM_MACRO_IO_LIBV8_H_
+#define ASM_MACRO_IO_LIBV8_H_
 
 // CurrentEL : 0xC = EL3; 8 = EL2; 4 = EL1
 // This only selects between EL1 and EL2, else we die.
@@ -54,4 +54,4 @@
   movk      Reg, ((Val) >> 16) & 0xffff, lsl #16  ; \
   movk      Reg, (Val) & 0xffff
 
-#endif // __MACRO_IO_LIBV8_H__
+#endif // ASM_MACRO_IO_LIBV8_H_
diff --git a/ArmPkg/Include/Chipset/AArch64.h b/ArmPkg/Include/Chipset/AArch64.h
index 09d4cfe28d..10aeb9a15a 100644
--- a/ArmPkg/Include/Chipset/AArch64.h
+++ b/ArmPkg/Include/Chipset/AArch64.h
@@ -7,8 +7,8 @@
 
 **/
 
-#ifndef __AARCH64_H__
-#define __AARCH64_H__
+#ifndef AARCH64_H_
+#define AARCH64_H_
 
 #include <Chipset/AArch64Mmu.h>
 
@@ -238,4 +238,4 @@ ArmWriteCntHctl (
   IN UINT32 CntHctl
   );
 
-#endif // __AARCH64_H__
+#endif // AARCH64_H_
diff --git a/ArmPkg/Include/Chipset/AArch64Mmu.h b/ArmPkg/Include/Chipset/AArch64Mmu.h
index 6c7ada16b1..fe38ba1c50 100644
--- a/ArmPkg/Include/Chipset/AArch64Mmu.h
+++ b/ArmPkg/Include/Chipset/AArch64Mmu.h
@@ -6,8 +6,8 @@
 *
 **/
 
-#ifndef __AARCH64_MMU_H_
-#define __AARCH64_MMU_H_
+#ifndef AARCH64_MMU_H_
+#define AARCH64_MMU_H_
 
 //
 // Memory Attribute Indirection register Definitions
@@ -194,5 +194,5 @@
 
 // Uses LPAE Page Table format
 
-#endif // __AARCH64_MMU_H_
+#endif // AARCH64_MMU_H_
 
diff --git a/ArmPkg/Include/Chipset/ArmCortexA9.h b/ArmPkg/Include/Chipset/ArmCortexA9.h
index 13d18e5893..cb937ebc8c 100644
--- a/ArmPkg/Include/Chipset/ArmCortexA9.h
+++ b/ArmPkg/Include/Chipset/ArmCortexA9.h
@@ -6,8 +6,8 @@
 
 **/
 
-#ifndef __ARM_CORTEX_A9_H__
-#define __ARM_CORTEX_A9_H__
+#ifndef ARM_CORTEX_A9_H_
+#define ARM_CORTEX_A9_H_
 
 #include <Chipset/ArmV7.h>
 
@@ -55,5 +55,5 @@ ArmGetScuBaseAddress (
   VOID
   );
 
-#endif
+#endif // ARM_CORTEX_A9_H_
 
diff --git a/ArmPkg/Include/Chipset/ArmV7.h b/ArmPkg/Include/Chipset/ArmV7.h
index 025f87a56d..6b20b988e3 100644
--- a/ArmPkg/Include/Chipset/ArmV7.h
+++ b/ArmPkg/Include/Chipset/ArmV7.h
@@ -7,8 +7,8 @@
 
 **/
 
-#ifndef __ARM_V7_H__
-#define __ARM_V7_H__
+#ifndef ARM_V7_H_
+#define ARM_V7_H_
 
 #include <Chipset/ArmV7Mmu.h>
 
@@ -120,4 +120,4 @@ ArmWriteNsacr (
   IN  UINT32   Nsacr
   );
 
-#endif // __ARM_V7_H__
+#endif // ARM_V7_H_
diff --git a/ArmPkg/Include/Chipset/ArmV7Mmu.h b/ArmPkg/Include/Chipset/ArmV7Mmu.h
index 25d82d0297..87c443df3f 100644
--- a/ArmPkg/Include/Chipset/ArmV7Mmu.h
+++ b/ArmPkg/Include/Chipset/ArmV7Mmu.h
@@ -6,8 +6,8 @@
 *
 **/
 
-#ifndef __ARMV7_MMU_H_
-#define __ARMV7_MMU_H_
+#ifndef ARMV7_MMU_H_
+#define ARMV7_MMU_H_
 
 #define TTBR_NOT_OUTER_SHAREABLE             BIT5
 #define TTBR_RGN_OUTER_NON_CACHEABLE         0
@@ -235,4 +235,4 @@ ConvertSectionAttributesToPageAttributes (
   IN BOOLEAN  IsLargePage
   );
 
-#endif
+#endif // ARMV7_MMU_H_
diff --git a/ArmPkg/Include/Guid/ArmMpCoreInfo.h b/ArmPkg/Include/Guid/ArmMpCoreInfo.h
index 3f9d17bb72..b810767879 100644
--- a/ArmPkg/Include/Guid/ArmMpCoreInfo.h
+++ b/ArmPkg/Include/Guid/ArmMpCoreInfo.h
@@ -6,8 +6,8 @@
 *
 **/
 
-#ifndef __ARM_MP_CORE_INFO_GUID_H_
-#define __ARM_MP_CORE_INFO_GUID_H_
+#ifndef ARM_MP_CORE_INFO_GUID_H_
+#define ARM_MP_CORE_INFO_GUID_H_
 
 #define MAX_CPUS_PER_MPCORE_SYSTEM    0x04
 #define SCU_CONFIG_REG_OFFSET         0x04
@@ -57,4 +57,4 @@ typedef struct {
 
 extern EFI_GUID gArmMpCoreInfoGuid;
 
-#endif /* MPCOREINFO_H_ */
+#endif /* ARM_MP_CORE_INFO_GUID_H_ */
diff --git a/ArmPkg/Include/IndustryStandard/ArmMmSvc.h b/ArmPkg/Include/IndustryStandard/ArmMmSvc.h
index 71a5398558..33d60ccf17 100644
--- a/ArmPkg/Include/IndustryStandard/ArmMmSvc.h
+++ b/ArmPkg/Include/IndustryStandard/ArmMmSvc.h
@@ -6,8 +6,8 @@
 *
 **/
 
-#ifndef __ARM_MM_SVC_H__
-#define __ARM_MM_SVC_H__
+#ifndef ARM_MM_SVC_H_
+#define ARM_MM_SVC_H_
 
 /*
  * SVC IDs to allow the MM secure partition to initialise itself, handle
@@ -44,4 +44,4 @@
 #define SPM_MAJOR_VERSION                     0
 #define SPM_MINOR_VERSION                     1
 
-#endif
+#endif // ARM_MM_SVC_H_
diff --git a/ArmPkg/Include/IndustryStandard/ArmStdSmc.h b/ArmPkg/Include/IndustryStandard/ArmStdSmc.h
index 9e0a3a3960..67afb0ea2d 100644
--- a/ArmPkg/Include/IndustryStandard/ArmStdSmc.h
+++ b/ArmPkg/Include/IndustryStandard/ArmStdSmc.h
@@ -10,8 +10,8 @@
 *    (https://developer.arm.com/documentation/den0028/c/?lang=en)
 **/
 
-#ifndef __ARM_STD_SMC_H__
-#define __ARM_STD_SMC_H__
+#ifndef ARM_STD_SMC_H_
+#define ARM_STD_SMC_H_
 
 /*
  * SMC function IDs for Standard Service queries
@@ -129,4 +129,4 @@
 /*                                    0xbf00ff02 is reserved */
 #define ARM_SMC_ID_TOS_REVISION       0xbf00ff03
 
-#endif
+#endif // ARM_STD_SMC_H_
diff --git a/ArmPkg/Include/Library/ArmDisassemblerLib.h b/ArmPkg/Include/Library/ArmDisassemblerLib.h
index c103b72e81..d8c7af029d 100644
--- a/ArmPkg/Include/Library/ArmDisassemblerLib.h
+++ b/ArmPkg/Include/Library/ArmDisassemblerLib.h
@@ -6,8 +6,8 @@
 
 **/
 
-#ifndef __ARM_DISASSEBLER_LIB_H__
-#define __ARM_DISASSEBLER_LIB_H__
+#ifndef ARM_DISASSEMBLER_LIB_H_
+#define ARM_DISASSEMBLER_LIB_H_
 
 /**
   Place a disassembly of **OpCodePtr into buffer, and update OpCodePtr to
@@ -34,4 +34,4 @@ DisassembleInstruction (
   OUT UINTN     Size
   );
 
-#endif
+#endif // ARM_DISASSEMBLER_LIB_H_
diff --git a/ArmPkg/Include/Library/ArmGenericTimerCounterLib.h b/ArmPkg/Include/Library/ArmGenericTimerCounterLib.h
index d3051be30f..96bdffbf1e 100644
--- a/ArmPkg/Include/Library/ArmGenericTimerCounterLib.h
+++ b/ArmPkg/Include/Library/ArmGenericTimerCounterLib.h
@@ -7,8 +7,8 @@
 
 **/
 
-#ifndef __ARM_GENERIC_TIMER_COUNTER_LIB_H__
-#define __ARM_GENERIC_TIMER_COUNTER_LIB_H__
+#ifndef ARM_GENERIC_TIMER_COUNTER_LIB_H_
+#define ARM_GENERIC_TIMER_COUNTER_LIB_H_
 
 VOID
 EFIAPI
@@ -82,4 +82,4 @@ ArmGenericTimerSetCompareVal (
   IN   UINT64   Value
   );
 
-#endif
+#endif // ARM_GENERIC_TIMER_COUNTER_LIB_H_
diff --git a/ArmPkg/Include/Library/ArmGicArchLib.h b/ArmPkg/Include/Library/ArmGicArchLib.h
index 264322f1d0..b3635d2268 100644
--- a/ArmPkg/Include/Library/ArmGicArchLib.h
+++ b/ArmPkg/Include/Library/ArmGicArchLib.h
@@ -6,8 +6,8 @@
 *
 **/
 
-#ifndef __ARM_GIC_ARCH_LIB_H__
-#define __ARM_GIC_ARCH_LIB_H__
+#ifndef ARM_GIC_ARCH_LIB_H_
+#define ARM_GIC_ARCH_LIB_H_
 
 //
 // GIC definitions
@@ -24,4 +24,4 @@ ArmGicGetSupportedArchRevision (
   VOID
   );
 
-#endif
+#endif // ARM_GIC_ARCH_LIB_H_
diff --git a/ArmPkg/Include/Library/ArmHvcLib.h b/ArmPkg/Include/Library/ArmHvcLib.h
index d26f0cff31..d202c2af6e 100644
--- a/ArmPkg/Include/Library/ArmHvcLib.h
+++ b/ArmPkg/Include/Library/ArmHvcLib.h
@@ -6,8 +6,8 @@
 *
 **/
 
-#ifndef __ARM_HVC_LIB__
-#define __ARM_HVC_LIB__
+#ifndef ARM_HVC_LIB_H_
+#define ARM_HVC_LIB_H_
 
 /**
  * The size of the HVC arguments are different between AArch64 and AArch32.
@@ -37,4 +37,4 @@ ArmCallHvc (
   IN OUT ARM_HVC_ARGS *Args
   );
 
-#endif
+#endif // ARM_HVC_LIB_H_
diff --git a/ArmPkg/Include/Library/ArmLib.h b/ArmPkg/Include/Library/ArmLib.h
index 70b9d816b7..5c232d779c 100644
--- a/ArmPkg/Include/Library/ArmLib.h
+++ b/ArmPkg/Include/Library/ArmLib.h
@@ -8,8 +8,8 @@
 
 **/
 
-#ifndef __ARM_LIB__
-#define __ARM_LIB__
+#ifndef ARM_LIB_H_
+#define ARM_LIB_H_
 
 #include <Uefi/UefiBaseType.h>
 
@@ -753,4 +753,4 @@ ArmHasSecurityExtensions (
   );
 #endif // MDE_CPU_ARM
 
-#endif // __ARM_LIB__
+#endif // ARM_LIB_H_
diff --git a/ArmPkg/Include/Library/ArmMmuLib.h b/ArmPkg/Include/Library/ArmMmuLib.h
index 23e89a0c65..410f06ce37 100644
--- a/ArmPkg/Include/Library/ArmMmuLib.h
+++ b/ArmPkg/Include/Library/ArmMmuLib.h
@@ -6,8 +6,8 @@
 
 **/
 
-#ifndef __ARM_MMU_LIB__
-#define __ARM_MMU_LIB__
+#ifndef ARM_MMU_LIB_H_
+#define ARM_MMU_LIB_H_
 
 #include <Uefi/UefiBaseType.h>
 
@@ -64,4 +64,4 @@ ArmSetMemoryAttributes (
   IN UINT64                    Attributes
   );
 
-#endif
+#endif // ARM_MMU_LIB_H_
diff --git a/ArmPkg/Include/Library/ArmSmcLib.h b/ArmPkg/Include/Library/ArmSmcLib.h
index 835d6788e0..ced60b3c11 100644
--- a/ArmPkg/Include/Library/ArmSmcLib.h
+++ b/ArmPkg/Include/Library/ArmSmcLib.h
@@ -6,8 +6,8 @@
 *
 **/
 
-#ifndef __ARM_SMC_LIB__
-#define __ARM_SMC_LIB__
+#ifndef ARM_SMC_LIB_H_
+#define ARM_SMC_LIB_H_
 
 /**
  * The size of the SMC arguments are different between AArch64 and AArch32.
@@ -37,4 +37,4 @@ ArmCallSmc (
   IN OUT ARM_SMC_ARGS *Args
   );
 
-#endif
+#endif // ARM_SMC_LIB_H_
diff --git a/ArmPkg/Include/Library/ArmSvcLib.h b/ArmPkg/Include/Library/ArmSvcLib.h
index a4414270f3..d4a1a8f118 100644
--- a/ArmPkg/Include/Library/ArmSvcLib.h
+++ b/ArmPkg/Include/Library/ArmSvcLib.h
@@ -6,8 +6,8 @@
 *
 **/
 
-#ifndef __ARM_SVC_LIB__
-#define __ARM_SVC_LIB__
+#ifndef ARM_SVC_LIB_H_
+#define ARM_SVC_LIB_H_
 
 /**
  * The size of the SVC arguments are different between AArch64 and AArch32.
@@ -43,4 +43,4 @@ ArmCallSvc (
   IN OUT ARM_SVC_ARGS *Args
   );
 
-#endif
+#endif // ARM_SVC_LIB_H_
diff --git a/ArmPkg/Include/Library/DefaultExceptionHandlerLib.h b/ArmPkg/Include/Library/DefaultExceptionHandlerLib.h
index bbcf30f857..57dc555e13 100644
--- a/ArmPkg/Include/Library/DefaultExceptionHandlerLib.h
+++ b/ArmPkg/Include/Library/DefaultExceptionHandlerLib.h
@@ -6,8 +6,8 @@
 
 **/
 
-#ifndef __DEFAULT_EXCEPTION_HANDLER_LIB_H__
-#define __DEFAULT_EXCEPTION_HANDLER_LIB_H__
+#ifndef DEFAULT_EXCEPTION_HANDLER_LIB_H_
+#define DEFAULT_EXCEPTION_HANDLER_LIB_H_
 
 /**
   This is the default action to take on an unexpected exception
@@ -22,4 +22,4 @@ DefaultExceptionHandler (
   IN OUT EFI_SYSTEM_CONTEXT           SystemContext
   );
 
-#endif
+#endif // DEFAULT_EXCEPTION_HANDLER_LIB_H_
diff --git a/ArmPkg/Include/Library/OpteeLib.h b/ArmPkg/Include/Library/OpteeLib.h
index 8ceab117d1..b9399d2e18 100644
--- a/ArmPkg/Include/Library/OpteeLib.h
+++ b/ArmPkg/Include/Library/OpteeLib.h
@@ -8,8 +8,8 @@
 
 **/
 
-#ifndef _OPTEE_H_
-#define _OPTEE_H_
+#ifndef OPTEE_LIB_H_
+#define OPTEE_LIB_H_
 
 /*
  * The 'Trusted OS Call UID' is supposed to return the following UUID for
@@ -117,4 +117,4 @@ OpteeInvokeFunction (
   IN OUT OPTEE_INVOKE_FUNCTION_ARG       *InvokeFunctionArg
   );
 
-#endif
+#endif // OPTEE_LIB_H_
diff --git a/ArmPkg/Include/Library/SemihostLib.h b/ArmPkg/Include/Library/SemihostLib.h
index ce08b2778d..590728c804 100644
--- a/ArmPkg/Include/Library/SemihostLib.h
+++ b/ArmPkg/Include/Library/SemihostLib.h
@@ -7,8 +7,8 @@
 
 **/
 
-#ifndef __SEMIHOSTING_H__
-#define __SEMIHOSTING_H__
+#ifndef SEMIHOSTING_LIB_H_
+#define SEMIHOSTING_LIB_H_
 
 /*
  *
@@ -129,4 +129,4 @@ SemihostSystem (
   IN CHAR8 *CommandLine
   );
 
-#endif // __SEMIHOSTING_H__
+#endif // SEMIHOSTING_LIB_H_
diff --git a/ArmPkg/Include/Library/StandaloneMmMmuLib.h b/ArmPkg/Include/Library/StandaloneMmMmuLib.h
index 1d2a0e0c2b..ccc016d035 100644
--- a/ArmPkg/Include/Library/StandaloneMmMmuLib.h
+++ b/ArmPkg/Include/Library/StandaloneMmMmuLib.h
@@ -6,8 +6,8 @@
 
 **/
 
-#ifndef __STANDALONEMM_MMU_LIB__
-#define __STANDALONEMM_MMU_LIB__
+#ifndef STANDALONE_MM_MMU_LIB_
+#define STANDALONE_MM_MMU_LIB_
 
 EFI_STATUS
 ArmSetMemoryRegionNoExec (
@@ -33,4 +33,4 @@ ArmClearMemoryRegionReadOnly (
   IN  UINT64                    Length
   );
 
-#endif /* __STANDALONEMM_MMU_LIB__ */
+#endif /* STANDALONE_MM_MMU_LIB_ */
diff --git a/ArmPkg/Include/Ppi/ArmMpCoreInfo.h b/ArmPkg/Include/Ppi/ArmMpCoreInfo.h
index 871119bde2..b1e404ce13 100644
--- a/ArmPkg/Include/Ppi/ArmMpCoreInfo.h
+++ b/ArmPkg/Include/Ppi/ArmMpCoreInfo.h
@@ -6,8 +6,8 @@
 *
 **/
 
-#ifndef __ARM_MP_CORE_INFO_PPI_H__
-#define __ARM_MP_CORE_INFO_PPI_H__
+#ifndef ARM_MP_CORE_INFO_PPI_H_
+#define ARM_MP_CORE_INFO_PPI_H_
 
 #include <Guid/ArmMpCoreInfo.h>
 
@@ -49,4 +49,4 @@ typedef struct {
 extern EFI_GUID gArmMpCoreInfoPpiGuid;
 extern EFI_GUID gArmMpCoreInfoGuid;
 
-#endif
+#endif // ARM_MP_CORE_INFO_PPI_H_
diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.h b/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.h
index cfc0c878a4..318020277b 100644
--- a/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.h
+++ b/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.h
@@ -8,8 +8,8 @@
 
 **/
 
-#ifndef __AARCH64_LIB_H__
-#define __AARCH64_LIB_H__
+#ifndef AARCH64_LIB_H_
+#define AARCH64_LIB_H_
 
 typedef VOID (*AARCH64_CACHE_OPERATION)(UINTN);
 
@@ -52,5 +52,5 @@ ArmReadIdAA64Mmfr2 (
   VOID
   );
 
-#endif // __AARCH64_LIB_H__
+#endif // AARCH64_LIB_H_
 
diff --git a/ArmPkg/Library/ArmLib/Arm/ArmV7Lib.h b/ArmPkg/Library/ArmLib/Arm/ArmV7Lib.h
index dcf6723b80..5a92ade2b3 100644
--- a/ArmPkg/Library/ArmLib/Arm/ArmV7Lib.h
+++ b/ArmPkg/Library/ArmLib/Arm/ArmV7Lib.h
@@ -6,8 +6,8 @@
 
 **/
 
-#ifndef __ARM_V7_LIB_H__
-#define __ARM_V7_LIB_H__
+#ifndef ARM_V7_LIB_H_
+#define ARM_V7_LIB_H_
 
 #define ID_MMFR0_SHARELVL_SHIFT       12
 #define ID_MMFR0_SHARELVL_MASK       0xf
@@ -64,5 +64,5 @@ ArmReadIdPfr1 (
   VOID
   );
 
-#endif // __ARM_V7_LIB_H__
+#endif // ARM_V7_LIB_H_
 
diff --git a/ArmPkg/Library/ArmLib/ArmLibPrivate.h b/ArmPkg/Library/ArmLib/ArmLibPrivate.h
index 1818a1994d..5db83d620b 100644
--- a/ArmPkg/Library/ArmLib/ArmLibPrivate.h
+++ b/ArmPkg/Library/ArmLib/ArmLibPrivate.h
@@ -8,8 +8,8 @@
 
 **/
 
-#ifndef __ARM_LIB_PRIVATE_H__
-#define __ARM_LIB_PRIVATE_H__
+#ifndef ARM_LIB_PRIVATE_H_
+#define ARM_LIB_PRIVATE_H_
 
 #define CACHE_SIZE_4_KB             (3UL)
 #define CACHE_SIZE_8_KB             (4UL)
@@ -186,4 +186,4 @@ ReadCLIDR (
   VOID
   );
 
-#endif // __ARM_LIB_PRIVATE_H__
+#endif // ARM_LIB_PRIVATE_H_
diff --git a/ArmPkg/Library/OpteeLib/OpteeSmc.h b/ArmPkg/Library/OpteeLib/OpteeSmc.h
index 62319d718d..b760ec8f82 100644
--- a/ArmPkg/Library/OpteeLib/OpteeSmc.h
+++ b/ArmPkg/Library/OpteeLib/OpteeSmc.h
@@ -7,8 +7,8 @@
 
 **/
 
-#ifndef _OPTEE_SMC_H_
-#define _OPTEE_SMC_H_
+#ifndef OPTEE_SMC_H_
+#define OPTEE_SMC_H_
 
 /* Returned in Arg0 only from Trusted OS functions */
 #define OPTEE_SMC_RETURN_OK                     0x0
@@ -47,4 +47,4 @@ typedef struct {
   UINT8   Data4[8];
 } RFC4122_UUID;
 
-#endif
+#endif // OPTEE_SMC_H_
diff --git a/ArmPkg/Library/PlatformBootManagerLib/PlatformBm.h b/ArmPkg/Library/PlatformBootManagerLib/PlatformBm.h
index 0bb3645ddc..a40a2ff5cb 100644
--- a/ArmPkg/Library/PlatformBootManagerLib/PlatformBm.h
+++ b/ArmPkg/Library/PlatformBootManagerLib/PlatformBm.h
@@ -9,8 +9,8 @@
 
 **/
 
-#ifndef _PLATFORM_BM_H_
-#define _PLATFORM_BM_H_
+#ifndef PLATFORM_BM_H_
+#define PLATFORM_BM_H_
 
 #include <Library/BaseLib.h>
 #include <Library/BaseMemoryLib.h>
@@ -50,4 +50,4 @@ DisableQuietBoot (
   VOID
   );
 
-#endif // _PLATFORM_BM_H_
+#endif // PLATFORM_BM_H_
diff --git a/ArmPkg/Library/SemihostLib/SemihostPrivate.h b/ArmPkg/Library/SemihostLib/SemihostPrivate.h
index 30103b04b5..8864726116 100644
--- a/ArmPkg/Library/SemihostLib/SemihostPrivate.h
+++ b/ArmPkg/Library/SemihostLib/SemihostPrivate.h
@@ -7,8 +7,8 @@
 
 **/
 
-#ifndef __SEMIHOST_PRIVATE_H__
-#define __SEMIHOST_PRIVATE_H__
+#ifndef SEMIHOST_PRIVATE_H_
+#define SEMIHOST_PRIVATE_H_
 
 typedef struct {
   CHAR8   *FileName;
@@ -209,4 +209,4 @@ GccSemihostCall (
 
 #endif // __CC_ARM
 
-#endif //__SEMIHOST_PRIVATE_H__
+#endif // SEMIHOST_PRIVATE_H_