Index: lib/libc/mips/gen/makecontext.c
===================================================================
--- lib/libc/mips/gen/makecontext.c
+++ lib/libc/mips/gen/makecontext.c
@@ -103,11 +103,14 @@
 	for (i = 0; i < argc && i < 8; i++)
 		/* LINTED register_t is safe */
 		mc->mc_regs[A0 + i] = va_arg(ap, register_t);
-	/* Pass remaining arguments on the stack above the $a0-3 gap. */
+	/* Pass remaining arguments on the stack above the $a0-7 gap. */
+	/*
+	 * XXX: Is this comment accurate?  There is no sp += i here to
+	 * match it for NEWABI.
+	 */
 #endif
-	/* Pass remaining arguments on the stack above the $a0-3 gap. */
 	for (; i < argc; i++)
-		/* LINTED uintptr_t is safe */
+		/* LINTED register_t is safe */
 		*sp++ = va_arg(ap, register_t);
 	va_end(ap);
 }
Index: sys/mips/include/md_var.h
===================================================================
--- sys/mips/include/md_var.h
+++ sys/mips/include/md_var.h
@@ -41,6 +41,17 @@
 /*
  * Miscellaneous machine-dependent declarations.
  */
+
+/*
+ * Use 16-byte stack alignment for N32 and N64 and 8-byte alignment
+ * for O32.  This matches the expectations of both GCC and LLVM.
+ */
+#if defined(__mips_n32) || defined(__mips_n64)
+#define	STACK_ALIGN	16
+#else
+#define	STACK_ALIGN	8
+#endif
+
 extern	long	Maxmem;
 extern	char	sigcode[];
 extern	int	szsigcode;
Index: sys/mips/mips/pm_machdep.c
===================================================================
--- sys/mips/mips/pm_machdep.c
+++ sys/mips/mips/pm_machdep.c
@@ -74,6 +74,12 @@
 
 #define	UCONTEXT_MAGIC	0xACEDBADE
 
+#if defined(__mips_n32) || defined(__mips_n64)
+#define	STACK_ALIGN	16
+#else
+#define	STACK_ALIGN	8
+#endif
+
 /*
  * Send an interrupt to process.
  *
@@ -132,10 +138,10 @@
 	    SIGISMEMBER(psp->ps_sigonstack, sig)) {
 		sfp = (struct sigframe *)(((uintptr_t)td->td_sigstk.ss_sp +
 		    td->td_sigstk.ss_size - sizeof(struct sigframe))
-		    & ~(sizeof(__int64_t) - 1));
+		    & ~(STACK_ALIGN - 1));
 	} else
 		sfp = (struct sigframe *)((vm_offset_t)(regs->sp - 
-		    sizeof(struct sigframe)) & ~(sizeof(__int64_t) - 1));
+		    sizeof(struct sigframe)) & ~(STACK_ALIGN - 1));
 
 	/* Build the argument list for the signal handler. */
 	regs->a0 = sig;
@@ -408,12 +414,7 @@
 
 	bzero((caddr_t)td->td_frame, sizeof(struct trapframe));
 
-	/*
-	 * The stack pointer has to be aligned to accommodate the largest
-	 * datatype at minimum.  This probably means it should be 16-byte
-	 * aligned, but for now we're 8-byte aligning it.
-	 */
-	td->td_frame->sp = ((register_t) stack) & ~(sizeof(__int64_t) - 1);
+	td->td_frame->sp = ((register_t)stack) & ~(STACK_ALIGN - 1);
 
 	/*
 	 * If we're running o32 or n32 programs but have 64-bit registers,
Index: sys/mips/mips/vm_machdep.c
===================================================================
--- sys/mips/mips/vm_machdep.c
+++ sys/mips/mips/vm_machdep.c
@@ -430,13 +430,7 @@
 	struct trapframe *tf;
 	register_t sp;
 
-	/*
-	 * At the point where a function is called, sp must be 8
-	 * byte aligned[for compatibility with 64-bit CPUs]
-	 * in ``See MIPS Run'' by D. Sweetman, p. 269
-	 * align stack
-	 */
-	sp = (((intptr_t)stack->ss_sp + stack->ss_size) & ~0x7) -
+	sp = (((intptr_t)stack->ss_sp + stack->ss_size) & ~(STACK_ALIGN - 1)) -
 	    CALLFRAME_SIZ;
 
 	/*