Index: llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
===================================================================
--- llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
+++ llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
@@ -336,12 +336,17 @@
   // instruction in which the current value is used, we cannot
   // stackify. Stackifying in this case would require that def moving below the
   // current def in the stack, which cannot be achieved, even with locals.
+  // Also ensure we don't sink the def past any other prior uses.
   for (const auto &SubsequentDef : drop_begin(DefI->defs())) {
-    for (const auto &PriorUse : UseI->uses()) {
-      if (&PriorUse == Use)
-        break;
-      if (PriorUse.isReg() && SubsequentDef.getReg() == PriorUse.getReg())
-        return false;
+    auto I = std::next(MachineBasicBlock::const_iterator(DefI));
+    auto E = std::next(MachineBasicBlock::const_iterator(UseI));
+    for (; I != E; ++I) {
+      for (const auto &PriorUse : I->uses()) {
+        if (&PriorUse == Use)
+          break;
+        if (PriorUse.isReg() && SubsequentDef.getReg() == PriorUse.getReg())
+          return false;
+      }
     }
   }
 
Index: llvm/test/CodeGen/WebAssembly/multivalue-dont-move-def-past-use.mir
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/WebAssembly/multivalue-dont-move-def-past-use.mir
@@ -0,0 +1,211 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=wasm32-unknown-unknown -mattr=+multivalue -run-pass=wasm-reg-stackify -verify-machineinstrs %s -o - | FileCheck %s
+--- |
+  target datalayout = "e-m:e-p:32:32-p10:8:8-p20:8:8-i64:64-n32:64-S128-ni:1:10:20"
+  target triple = "wasm32-unknown-unknown"
+
+  @d = hidden local_unnamed_addr global double 0.000000e+00, align 8
+  @c = hidden local_unnamed_addr global i32 0, align 4
+
+  define hidden fp128 @e() local_unnamed_addr #0 {
+    %1 = load double, ptr @d, align 8
+    %2 = fcmp une double %1, 0.000000e+00
+    br i1 %2, label %9, label %3
+
+  3:                                                ; preds = %0
+    %4 = load i32, ptr @c, align 4
+    %5 = icmp eq i32 %4, 0
+    %6 = fptosi double %1 to i32
+    %7 = sitofp i32 %6 to fp128
+    %8 = select i1 %5, fp128 0xL00000000000000000000000000000000, fp128 %7
+    br label %9
+
+  9:                                                ; preds = %3, %0
+    %10 = phi fp128 [ %8, %3 ], [ 0xL00000000000000000000000000000000, %0 ]
+    ret fp128 %10
+  }
+
+  attributes #0 = { "target-features"="+multivalue,+mutable-globals,+sign-ext," }
+
+  !llvm.module.flags = !{!0, !1, !2}
+
+  !0 = !{i32 1, !"wasm-feature-multivalue", i32 43}
+  !1 = !{i32 1, !"wasm-feature-mutable-globals", i32 43}
+  !2 = !{i32 1, !"wasm-feature-sign-ext", i32 43}
+
+...
+---
+name:            e
+alignment:       1
+exposesReturnsTwice: false
+legalized:       false
+regBankSelected: false
+selected:        false
+failedISel:      false
+tracksRegLiveness: true
+hasWinCFI:       false
+callsEHReturn:   false
+callsUnwindInit: false
+hasEHCatchret:   false
+hasEHScopes:     false
+hasEHFunclets:   false
+failsVerification: false
+tracksDebugUserValues: false
+registers:
+  - { id: 0, class: f64, preferred-register: '' }
+  - { id: 1, class: i64, preferred-register: '' }
+  - { id: 2, class: i64, preferred-register: '' }
+  - { id: 3, class: i64, preferred-register: '' }
+  - { id: 4, class: i64, preferred-register: '' }
+  - { id: 5, class: i64, preferred-register: '' }
+  - { id: 6, class: i64, preferred-register: '' }
+  - { id: 7, class: i32, preferred-register: '' }
+  - { id: 8, class: f64, preferred-register: '' }
+  - { id: 9, class: i32, preferred-register: '' }
+  - { id: 10, class: i32, preferred-register: '' }
+  - { id: 11, class: i32, preferred-register: '' }
+  - { id: 12, class: i32, preferred-register: '' }
+  - { id: 13, class: i64, preferred-register: '' }
+  - { id: 14, class: i64, preferred-register: '' }
+  - { id: 15, class: i64, preferred-register: '' }
+  - { id: 16, class: f64, preferred-register: '' }
+  - { id: 17, class: f64, preferred-register: '' }
+  - { id: 18, class: i32, preferred-register: '' }
+  - { id: 19, class: i32, preferred-register: '' }
+  - { id: 20, class: i32, preferred-register: '' }
+  - { id: 21, class: i32, preferred-register: '' }
+  - { id: 22, class: i32, preferred-register: '' }
+  - { id: 23, class: i64, preferred-register: '' }
+  - { id: 24, class: i64, preferred-register: '' }
+liveins:
+  - { reg: '$arguments', virtual-reg: '' }
+frameInfo:
+  isFrameAddressTaken: false
+  isReturnAddressTaken: false
+  hasStackMap:     false
+  hasPatchPoint:   false
+  stackSize:       0
+  offsetAdjustment: 0
+  maxAlignment:    1
+  adjustsStack:    false
+  hasCalls:        true
+  stackProtector:  ''
+  functionContext: ''
+  maxCallFrameSize: 0
+  cvBytesOfCalleeSavedRegisters: 0
+  hasOpaqueSPAdjustment: false
+  hasVAStart:      false
+  hasMustTailInVarArgFunc: false
+  hasTailCall:     false
+  localFrameSize:  0
+  savePoint:       ''
+  restorePoint:    ''
+fixedStack:      []
+stack:           []
+callSites:       []
+debugValueSubstitutions: []
+constants:       []
+machineFunctionInfo:
+  params:          [  ]
+  results:         [ i64, i64 ]
+  isCFGStackified: false
+  wasmEHFuncInfo:  {}
+body:             |
+  ; CHECK-LABEL: name: e
+  ; CHECK: bb.0 (%ir-block.0):
+  ; CHECK-NEXT:   successors: %bb.5(0x50000000), %bb.1(0x30000000)
+  ; CHECK-NEXT:   liveins: $arguments, $value_stack
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[CONST_I64_:%[0-9]+]]:i64 = CONST_I64 0, implicit-def dead $arguments
+  ; CHECK-NEXT:   [[CONST_I64_1:%[0-9]+]]:i64 = CONST_I64 0, implicit-def dead $arguments
+  ; CHECK-NEXT:   [[CONST_I32_:%[0-9]+]]:i32 = CONST_I32 0, implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+  ; CHECK-NEXT:   [[LOAD_F64_A32_:%[0-9]+]]:f64 = LOAD_F64_A32 3, @d, [[CONST_I32_]], implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack :: (dereferenceable load (s64) from @d)
+  ; CHECK-NEXT:   [[TEE_F64_:%[0-9]+]]:f64, [[TEE_F64_1:%[0-9]+]]:f64 = TEE_F64 [[LOAD_F64_A32_]], implicit-def $arguments, implicit-def $value_stack, implicit $value_stack
+  ; CHECK-NEXT:   [[CONST_F64_:%[0-9]+]]:f64 = CONST_F64 double 0.000000e+00, implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+  ; CHECK-NEXT:   [[NE_F64_:%[0-9]+]]:i32 = NE_F64 [[TEE_F64_]], [[CONST_F64_]], implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+  ; CHECK-NEXT:   BR_IF %bb.5, [[NE_F64_]], implicit-def $arguments, implicit-def $value_stack, implicit $value_stack
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.1 (%ir-block.3):
+  ; CHECK-NEXT:   successors: %bb.3(0x40000000), %bb.2(0x40000000)
+  ; CHECK-NEXT:   liveins: $value_stack
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[CONST_I32_1:%[0-9]+]]:i32 = CONST_I32 0, implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+  ; CHECK-NEXT:   [[LOAD_I32_A32_:%[0-9]+]]:i32 = LOAD_I32_A32 2, @c, [[CONST_I32_1]], implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack :: (dereferenceable load (s32) from @c)
+  ; CHECK-NEXT:   [[ABS_F64_:%[0-9]+]]:f64 = ABS_F64 [[TEE_F64_1]], implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+  ; CHECK-NEXT:   [[CONST_F64_1:%[0-9]+]]:f64 = CONST_F64 double 0x41E0000000000000, implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+  ; CHECK-NEXT:   [[LT_F64_:%[0-9]+]]:i32 = LT_F64 [[ABS_F64_]], [[CONST_F64_1]], implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+  ; CHECK-NEXT:   [[EQZ_I32_:%[0-9]+]]:i32 = EQZ_I32 [[LT_F64_]], implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+  ; CHECK-NEXT:   BR_IF %bb.3, [[EQZ_I32_]], implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.2 (%ir-block.3):
+  ; CHECK-NEXT:   successors: %bb.4(0x80000000)
+  ; CHECK-NEXT:   liveins: $value_stack
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[I32_TRUNC_S_F64_:%[0-9]+]]:i32 = I32_TRUNC_S_F64 [[TEE_F64_1]], implicit-def dead $arguments
+  ; CHECK-NEXT:   BR %bb.4, implicit-def $arguments
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.3 (%ir-block.3):
+  ; CHECK-NEXT:   successors: %bb.4(0x80000000)
+  ; CHECK-NEXT:   liveins: $value_stack
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[CONST_I32_2:%[0-9]+]]:i32 = CONST_I32 -2147483648, implicit-def dead $arguments
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.4 (%ir-block.3):
+  ; CHECK-NEXT:   successors: %bb.5(0x80000000)
+  ; CHECK-NEXT:   liveins: $value_stack
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[CALL:%[0-9]+]]:i64, [[CALL1:%[0-9]+]]:i64 = CALL &__floatsitf, [[CONST_I32_2]], implicit-def dead $arguments, implicit $sp32, implicit $sp64, implicit-def dead $arguments, implicit $sp32, implicit $sp64
+  ; CHECK-NEXT:   [[CONST_I64_2:%[0-9]+]]:i64 = CONST_I64 0, implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+  ; CHECK-NEXT:   [[SELECT_I64_:%[0-9]+]]:i64 = SELECT_I64 [[CALL1]], [[CONST_I64_2]], [[LOAD_I32_A32_]], implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+  ; CHECK-NEXT:   [[CONST_I64_2:%[0-9]+]]:i64 = CONST_I64 0, implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+  ; CHECK-NEXT:   [[SELECT_I64_1:%[0-9]+]]:i64 = SELECT_I64 [[CALL]], [[CONST_I64_2]], [[LOAD_I32_A32_]], implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.5 (%ir-block.9):
+  ; CHECK-NEXT:   liveins: $value_stack
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   RETURN [[SELECT_I64_1]], [[SELECT_I64_]], implicit-def dead $arguments
+  bb.0 (%ir-block.0):
+    successors: %bb.5(0x50000000), %bb.1(0x30000000)
+    liveins: $arguments
+
+    %7:i32 = CONST_I32 0, implicit-def dead $arguments
+    %0:f64 = LOAD_F64_A32 3, @d, %7, implicit-def dead $arguments :: (dereferenceable load (s64) from @d)
+    %8:f64 = CONST_F64 double 0.000000e+00, implicit-def dead $arguments
+    %9:i32 = NE_F64 %0, %8, implicit-def dead $arguments
+    %23:i64 = CONST_I64 0, implicit-def dead $arguments
+    %24:i64 = CONST_I64 0, implicit-def dead $arguments
+    BR_IF %bb.5, %9, implicit-def $arguments
+
+  bb.1 (%ir-block.3):
+    successors: %bb.3(0x40000000), %bb.2(0x40000000)
+
+    %11:i32 = LOAD_I32_A32 2, @c, %7, implicit-def dead $arguments :: (dereferenceable load (s32) from @c)
+    %16:f64 = ABS_F64 %0, implicit-def dead $arguments
+    %17:f64 = CONST_F64 double 0x41E0000000000000, implicit-def dead $arguments
+    %18:i32 = LT_F64 %16, %17, implicit-def dead $arguments
+    %19:i32 = EQZ_I32 %18, implicit-def dead $arguments
+    BR_IF %bb.3, %19, implicit-def dead $arguments
+
+  bb.2 (%ir-block.3):
+    successors: %bb.4(0x80000000)
+
+    %22:i32 = I32_TRUNC_S_F64 %0, implicit-def dead $arguments
+    BR %bb.4, implicit-def $arguments
+
+  bb.3 (%ir-block.3):
+    successors: %bb.4(0x80000000)
+
+    %22:i32 = CONST_I32 -2147483648, implicit-def dead $arguments
+
+  bb.4 (%ir-block.3):
+    successors: %bb.5(0x80000000)
+
+    %13:i64 = CONST_I64 0, implicit-def dead $arguments
+    %14:i64, %15:i64 = CALL &__floatsitf, %22, implicit-def dead $arguments, implicit $sp32, implicit $sp64, implicit-def dead $arguments, implicit $sp32, implicit $sp64
+    %24:i64 = SELECT_I64 %15, %13, %11, implicit-def dead $arguments
+    %23:i64 = SELECT_I64 %14, %13, %11, implicit-def dead $arguments
+
+  bb.5 (%ir-block.9):
+    RETURN %23, %24, implicit-def dead $arguments
+
+...