diff --git a/ArmPkg/ArmPkg.dec b/ArmPkg/ArmPkg.dec
index debe066b6f..3aa229fe2e 100644
--- a/ArmPkg/ArmPkg.dec
+++ b/ArmPkg/ArmPkg.dec
@@ -85,6 +85,10 @@
   # Define if the GICv3 controller should use the GICv2 legacy
   gArmTokenSpaceGuid.PcdArmGicV3WithV2Legacy|FALSE|BOOLEAN|0x00000042
 
+  # Whether to implement warm reboot for capsule update using a jump back to the
+  # PEI entry point with caches and interrupts disabled.
+  gArmTokenSpaceGuid.PcdArmReenterPeiForCapsuleWarmReboot|FALSE|BOOLEAN|0x0000001F
+
 [PcdsFeatureFlag.ARM]
   # Whether to map normal memory as non-shareable. FALSE is the safe choice, but
   # TRUE may be appropriate to fix performance problems if you don't care about
diff --git a/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c b/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c
index d6d26bce50..10ceafd14d 100644
--- a/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c
+++ b/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c
@@ -15,10 +15,13 @@
 
 #include <PiDxe.h>
 
+#include <Library/ArmMmuLib.h>
+#include <Library/ArmSmcLib.h>
 #include <Library/BaseLib.h>
 #include <Library/DebugLib.h>
 #include <Library/ResetSystemLib.h>
-#include <Library/ArmSmcLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiRuntimeLib.h>
 
 #include <IndustryStandard/ArmStdSmc.h>
 
@@ -89,7 +92,21 @@ EnterS3WithImmediateWake (
   VOID
   )
 {
-  // Not implemented
+  VOID (*Reset)(VOID);
+
+  if (FeaturePcdGet (PcdArmReenterPeiForCapsuleWarmReboot) &&
+      !EfiAtRuntime ()) {
+    //
+    // At boot time, we are the only core running, so we can implement the
+    // immediate wake (which is used by capsule update) by disabling the MMU
+    // and interrupts, and jumping to the PEI entry point.
+    //
+    Reset = (VOID (*)(VOID))(UINTN)FixedPcdGet64 (PcdFvBaseAddress);
+
+    gBS->RaiseTPL (TPL_HIGH_LEVEL);
+    ArmDisableMmu ();
+    Reset ();
+  }
 }
 
 /**
diff --git a/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.inf b/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.inf
index 5a1ee976e5..19021cd1e8 100644
--- a/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.inf
+++ b/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.inf
@@ -30,6 +30,15 @@
   MdePkg/MdePkg.dec
 
 [LibraryClasses]
+  ArmMmuLib
   ArmSmcLib
   BaseLib
   DebugLib
+  UefiBootServicesTableLib
+  UefiRuntimeLib
+
+[FeaturePcd]
+  gArmTokenSpaceGuid.PcdArmReenterPeiForCapsuleWarmReboot
+
+[FixedPcd]
+  gArmTokenSpaceGuid.PcdFvBaseAddress