Index: lib/Target/X86/X86FrameLowering.cpp
===================================================================
--- lib/Target/X86/X86FrameLowering.cpp
+++ lib/Target/X86/X86FrameLowering.cpp
@@ -959,6 +959,15 @@
         .getValueAsString()
         .getAsInteger(0, StackProbeSize);
 
+  // Re-align the stack on 64-bit if the x86-interrupt calling convention is used
+  // and an error code was pushed, since the x86-64 ABI requires a 16-byte stack
+  // alignment.
+  if (Fn->getCallingConv() == CallingConv::X86_INTR && Is64Bit && Fn->arg_size() == 2) {
+    StackSize += 8;
+    MFI.setStackSize(StackSize);
+    emitSPUpdate(MBB, MBBI, -8, /*InEpilogue=*/false);
+  }
+
   // If this is x86-64 and the Red Zone is not disabled, if we are a leaf
   // function, and use up to 128 bytes of stack space, don't have a frame
   // pointer, calls, or dynamic alloca then we do not need to adjust the
Index: lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- lib/Target/X86/X86ISelLowering.cpp
+++ lib/Target/X86/X86ISelLowering.cpp
@@ -2697,6 +2697,11 @@
     // Offset of last argument need to be set to -4/-8 bytes.
     // Where offset of the first argument out of two, should be set to 0 bytes.
     Offset = (Subtarget.is64Bit() ? 8 : 4) * ((i + 1) % Ins.size() - 1);
+    if (Subtarget.is64Bit() && Ins.size() == 2) {
+      // The stack pointer needs to be realigned for 64 bit handlers with error
+      // code, so the argument offset changes by 8 bytes.
+      Offset += 8;
+    }
   }
 
   // FIXME: For now, all byval parameter objects are marked mutable. This can be
@@ -3113,8 +3118,9 @@
                        MF.getTarget().Options.GuaranteedTailCallOpt)) {
     FuncInfo->setBytesToPopOnReturn(StackSize); // Callee pops everything.
   } else if (CallConv == CallingConv::X86_INTR && Ins.size() == 2) {
-    // X86 interrupts must pop the error code if present
-    FuncInfo->setBytesToPopOnReturn(Is64Bit ? 8 : 4);
+    // X86 interrupts must pop the error code (and the alignment padding)
+    // if present.
+    FuncInfo->setBytesToPopOnReturn(Is64Bit ? 16 : 4);
   } else {
     FuncInfo->setBytesToPopOnReturn(0); // Callee pops nothing.
     // If this is an sret function, the return should pop the hidden pointer.
Index: test/CodeGen/X86/x86-64-intrcc-nosse.ll
===================================================================
--- test/CodeGen/X86/x86-64-intrcc-nosse.ll
+++ test/CodeGen/X86/x86-64-intrcc-nosse.ll
@@ -9,10 +9,11 @@
 define x86_intrcc void @test_isr_sse_clobbers(%struct.interrupt_frame* %frame, i64 %ecode) {
   ; CHECK-LABEL: test_isr_sse_clobbers:
   ; CHECK:       # BB#0:
+  ; CHECK-NEXT:    pushq %rax
   ; CHECK-NEXT:    cld
   ; CHECK-NEXT:    #APP
   ; CHECK-NEXT:    #NO_APP
-  ; CHECK-NEXT:    addq $8, %rsp
+  ; CHECK-NEXT:    addq $16, %rsp
   ; CHECK-NEXT:    iretq
   call void asm sideeffect "", "~{xmm0},~{xmm6}"()
   ret void
Index: test/CodeGen/X86/x86-64-intrcc.ll
===================================================================
--- test/CodeGen/X86/x86-64-intrcc.ll
+++ test/CodeGen/X86/x86-64-intrcc.ll
@@ -30,22 +30,24 @@
 define x86_intrcc void @test_isr_ecode(%struct.interrupt_frame* %frame, i64 %ecode) {
   ; CHECK-LABEL: test_isr_ecode
   ; CHECK: pushq %rax
+  ; CHECK: pushq %rax
   ; CHECK: pushq %rcx
-  ; CHECK: movq 16(%rsp), %rax
-  ; CHECK: movq 40(%rsp), %rcx
+  ; CHECK: movq 24(%rsp), %rax
+  ; CHECK: movq 48(%rsp), %rcx
   ; CHECK: popq %rcx
   ; CHECK: popq %rax
-  ; CHECK: addq $8, %rsp
+  ; CHECK: addq $16, %rsp
   ; CHECK: iretq
   ; CHECK0-LABEL: test_isr_ecode
   ; CHECK0: pushq %rax
+  ; CHECK0: pushq %rax
   ; CHECK0: pushq %rcx
-  ; CHECK0: movq 16(%rsp), %rax
-  ; CHECK0: leaq 24(%rsp), %rcx
+  ; CHECK0: movq 24(%rsp), %rax
+  ; CHECK0: leaq 32(%rsp), %rcx
   ; CHECK0: movq 16(%rcx), %rcx
   ; CHECK0: popq %rcx
   ; CHECK0: popq %rax
-  ; CHECK0: addq $8, %rsp
+  ; CHECK0: addq $16, %rsp
   ; CHECK0: iretq
   %pflags = getelementptr inbounds %struct.interrupt_frame, %struct.interrupt_frame* %frame, i32 0, i32 2
   %flags = load i64, i64* %pflags, align 4
@@ -58,6 +60,7 @@
   call void asm sideeffect "", "~{rax},~{rbx},~{rbp},~{r11},~{xmm0}"()
   ; CHECK-LABEL: test_isr_clobbers
   ; CHECK-SSE-NEXT: pushq %rax
+  ; CHECK-SSE-NEXT: pushq %rax
   ; CHECK-SSE-NEXT; pushq %r11
   ; CHECK-SSE-NEXT: pushq %rbp
   ; CHECK-SSE-NEXT: pushq %rbx
@@ -67,10 +70,11 @@
   ; CHECK-SSE-NEXT: popq %rbp
   ; CHECK-SSE-NEXT: popq %r11
   ; CHECK-SSE-NEXT: popq %rax
-  ; CHECK-SSE-NEXT: addq $8, %rsp
+  ; CHECK-SSE-NEXT: addq $16, %rsp
   ; CHECK-SSE-NEXT: iretq
   ; CHECK0-LABEL: test_isr_clobbers
   ; CHECK0-SSE-NEXT: pushq %rax
+  ; CHECK0-SSE-NEXT: pushq %rax
   ; CHECK0-SSE-NEXT; pushq %r11
   ; CHECK0-SSE-NEXT: pushq %rbp
   ; CHECK0-SSE-NEXT: pushq %rbx
@@ -80,7 +84,7 @@
   ; CHECK0-SSE-NEXT: popq %rbp
   ; CHECK0-SSE-NEXT: popq %r11
   ; CHECK0-SSE-NEXT: popq %rax
-  ; CHECK0-SSE-NEXT: addq $8, %rsp
+  ; CHECK0-SSE-NEXT: addq $16, %rsp
   ; CHECK0-SSE-NEXT: iretq
   ret void
 }