diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index a67b971c830a77c7651c52d89e9562d10ccea964..f9e84da49716dd0c71ba0625788713e9f0c52ace 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -586,6 +586,30 @@ config NUMA
 	  Access).  This option is for configuring high-end multiprocessor
 	  server machines.  If in doubt, say N.
 
+config ALPHA_WTINT
+	bool "Use WTINT" if ALPHA_SRM || ALPHA_GENERIC
+	default y if ALPHA_QEMU
+	default n if ALPHA_EV5 || ALPHA_EV56 || (ALPHA_EV4 && !ALPHA_LCA)
+	default n if !ALPHA_SRM && !ALPHA_GENERIC
+	default y if SMP
+	---help---
+	  The Wait for Interrupt (WTINT) PALcall attempts to place the CPU
+	  to sleep until the next interrupt.  This may reduce the power
+	  consumed, and the heat produced by the computer.  However, it has
+	  the side effect of making the cycle counter unreliable as a timing
+	  device across the sleep.
+
+	  For emulation under QEMU, definitely say Y here, as we have other
+	  mechanisms for measuring time than the cycle counter.
+
+	  For EV4 (but not LCA), EV5 and EV56 systems, or for systems running
+	  MILO, sleep mode is not supported so you might as well say N here.
+
+	  For SMP systems we cannot use the cycle counter for timing anyway,
+	  so you might as well say Y here.
+
+	  If unsure, say N.
+
 config NODES_SHIFT
 	int
 	default "7"
diff --git a/arch/alpha/include/asm/pal.h b/arch/alpha/include/asm/pal.h
index 6fcd2b5b08f0d5ac4462ba6616a66519c2819d7d..e78ec9bcc768a88d2e330b3bc855fe384cb52bb1 100644
--- a/arch/alpha/include/asm/pal.h
+++ b/arch/alpha/include/asm/pal.h
@@ -89,6 +89,7 @@ __CALL_PAL_W1(wrmces, unsigned long);
 __CALL_PAL_RW2(wrperfmon, unsigned long, unsigned long, unsigned long);
 __CALL_PAL_W1(wrusp, unsigned long);
 __CALL_PAL_W1(wrvptptr, unsigned long);
+__CALL_PAL_RW1(wtint, unsigned long, unsigned long);
 
 /*
  * TB routines..
diff --git a/arch/alpha/include/uapi/asm/pal.h b/arch/alpha/include/uapi/asm/pal.h
index 3c0ce08e5f592d9b779c10a441527cd9061e9c07..dfc8140b908821d46a3d82f30baaa121c1bf64ef 100644
--- a/arch/alpha/include/uapi/asm/pal.h
+++ b/arch/alpha/include/uapi/asm/pal.h
@@ -46,6 +46,7 @@
 #define PAL_rdusp	58
 #define PAL_whami	60
 #define PAL_retsys	61
+#define PAL_wtint	62
 #define PAL_rti		63
 
 
diff --git a/arch/alpha/kernel/process.c b/arch/alpha/kernel/process.c
index f2360a74e5d5544983160d951c46bddb98819e0e..1941a07b5811f925aed82e853aab4efb081f74ca 100644
--- a/arch/alpha/kernel/process.c
+++ b/arch/alpha/kernel/process.c
@@ -46,6 +46,23 @@
 void (*pm_power_off)(void) = machine_power_off;
 EXPORT_SYMBOL(pm_power_off);
 
+#ifdef CONFIG_ALPHA_WTINT
+/*
+ * Sleep the CPU.
+ * EV6, LCA45 and QEMU know how to power down, skipping N timer interrupts.
+ */
+void arch_cpu_idle(void)
+{
+	wtint(0);
+	local_irq_enable();
+}
+
+void arch_cpu_idle_dead(void)
+{
+	wtint(INT_MAX);
+}
+#endif /* ALPHA_WTINT */
+
 struct halt_info {
 	int mode;
 	char *restart_cmd;
diff --git a/arch/alpha/kernel/traps.c b/arch/alpha/kernel/traps.c
index bd0665cdc840d3e9a79b752ec3a88279ede69344..9c4c189eb22f5a9db2d2ae678756a5241b3e1ee5 100644
--- a/arch/alpha/kernel/traps.c
+++ b/arch/alpha/kernel/traps.c
@@ -241,6 +241,21 @@ do_entIF(unsigned long type, struct pt_regs *regs)
 			       (const char *)(data[1] | (long)data[2] << 32), 
 			       data[0]);
 		}
+#ifdef CONFIG_ALPHA_WTINT
+		if (type == 4) {
+			/* If CALL_PAL WTINT is totally unsupported by the
+			   PALcode, e.g. MILO, "emulate" it by overwriting
+			   the insn.  */
+			unsigned int *pinsn
+			  = (unsigned int *) regs->pc - 1;
+			if (*pinsn == PAL_wtint) {
+				*pinsn = 0x47e01400; /* mov 0,$0 */
+				imb();
+				regs->r0 = 0;
+				return;
+			}
+		}
+#endif /* ALPHA_WTINT */
 		die_if_kernel((type == 1 ? "Kernel Bug" : "Instruction fault"),
 			      regs, type, NULL);
 	}