diff --git a/llvm/lib/CodeGen/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -135,6 +135,10 @@
       // defined. Map value is the user.
       RegMap vregsLiveIn;
 
+      // Key is the src MO in PHI node, Value is the MBB which the MO is from.
+      std::multimap<const MachineOperand *,
+                    const MachineBasicBlock *> PHIVarFrom;
+
       // Regs killed in MBB. They may be defined again, and will then be in both
       // regsKilled and regsLiveOut.
       RegSet regsKilled;
@@ -1465,6 +1469,13 @@
 
     if (FirstNonPHI)
       report("Found PHI instruction after non-PHI", MI);
+
+    // Record the MBB which the src MO of PHI node is from.
+    for (unsigned i = 1, e = MI->getNumOperands(); i != e; i += 2) {
+      BBInfo &MInfo = MBBInfoMap[MI->getParent()];
+      MInfo.PHIVarFrom.insert(std::make_pair(&MI->getOperand(i),
+                              MI->getOperand(i + 1).getMBB()));
+    }
   } else if (FirstNonPHI == nullptr)
     FirstNonPHI = MI;
 
@@ -2290,6 +2301,25 @@
       if (PInfo.addRequired(MInfo.vregsLiveIn))
         todo.insert(Pred);
     }
+
+    // Handle the PHI node.
+    for (const auto &I : MInfo.PHIVarFrom) {
+      unsigned Reg = I.first->getReg();
+
+      // If the Reg is in MInfo.vregsLiveIn, it has been added to vregsRequired.
+      if (MInfo.vregsLiveIn.find(Reg) == MInfo.vregsLiveIn.end() &&
+          Register::isVirtualRegister(Reg) &&
+          I.first->readsReg()) {
+        const MachineBasicBlock *FromMBB = I.second;
+        BBInfo &PInfo = MBBInfoMap[FromMBB];
+
+        // For the src Reg in PHI node, its DefBlock of LiveVariable should be
+        // different with its FromMBB.
+        if (MRI->getVRegDef(Reg)->getParent() != FromMBB &&
+            PInfo.addRequired(Reg))
+          todo.insert(FromMBB);
+      }
+    }
   }
 
   // Iteratively push vregsRequired to predecessors. This will converge to the
diff --git a/llvm/test/CodeGen/PowerPC/livevars-crash1.mir b/llvm/test/CodeGen/PowerPC/livevars-crash1.mir
--- a/llvm/test/CodeGen/PowerPC/livevars-crash1.mir
+++ b/llvm/test/CodeGen/PowerPC/livevars-crash1.mir
@@ -1,6 +1,5 @@
-# RUN: not --crash llc -mtriple powerpc64le-unknown-linux-gnu %s -o - 2>&1 \
-# RUN:   -run-pass=livevars,phi-node-elimination -verify-machineinstrs \
-# RUN:   | FileCheck %s
+# RUN: llc -mtriple powerpc64le-unknown-linux-gnu %s -o - 2>&1 \
+# RUN:   -run-pass=livevars,phi-node-elimination -verify-machineinstrs
 
 --- |
   ; Function Attrs: noreturn nounwind
@@ -83,8 +82,12 @@
     B %bb.1
 
 ...
-# CHECK-LABEL: Bad machine code: LiveVariables: Block should not be in AliveBlocks
-# CHECK-NEXT:  - function:    zext_free
-# CHECK-NEXT:  - basic block: %bb.2 loop
-# CHECK-NEXT:  Virtual register %2 is not needed live through the block.
-# CHECK-NEXT:  LLVM ERROR: Found 1 machine code errors.
+# Used to result in
+#
+# Bad machine code: LiveVariables: Block should not be in AliveBlocks
+# - function:    zext_free
+# - basic block: %bb.2 loop
+# Virtual register %2 is not needed live through the block.
+# LLVM ERROR: Found 1 machine code errors.
+#
+# Just verify that we do not crash (or get verifier error).
diff --git a/llvm/test/CodeGen/PowerPC/livevars-crash2.mir b/llvm/test/CodeGen/PowerPC/livevars-crash2.mir
--- a/llvm/test/CodeGen/PowerPC/livevars-crash2.mir
+++ b/llvm/test/CodeGen/PowerPC/livevars-crash2.mir
@@ -1,6 +1,5 @@
-# RUN: not --crash llc -mtriple powerpc64le-unknown-linux-gnu %s -o - 2>&1 \
-# RUN:   -run-pass=livevars,phi-node-elimination -verify-machineinstrs \
-# RUN:   | FileCheck %s
+# RUN: llc -mtriple powerpc64le-unknown-linux-gnu %s -o - 2>&1 \
+# RUN:   -run-pass=livevars,phi-node-elimination -verify-machineinstrs
 
 --- |
   define float @testfloatslt(float %c1, float %c2, float %c3, float %c4, float %a1, float %a2) {
@@ -177,19 +176,22 @@
     B %bb.1
 
 ...
+# Used to result in
+#
+# Bad machine code: LiveVariables: Block should not be in AliveBlocks
+# - function:    testfloatslt
+# - basic block: %bb.1 entry
+# Virtual register %4 is not needed live through the block.
 
-# CHECK-LABEL: Bad machine code: LiveVariables: Block should not be in AliveBlocks
-# CHECK-NEXT:  - function:    testfloatslt
-# CHECK-NEXT:  - basic block: %bb.1 entry
-# CHECK-NEXT:  Virtual register %4 is not needed live through the block.
+# Bad machine code: LiveVariables: Block should not be in AliveBlocks
+# - function:    testfloatslt
+# - basic block: %bb.1 entry
+# Virtual register %5 is not needed live through the block.
 
-# CHECK-LABEL: Bad machine code: LiveVariables: Block should not be in AliveBlocks
-# CHECK-NEXT:  - function:    testfloatslt
-# CHECK-NEXT:  - basic block: %bb.1 entry
-# CHECK-NEXT:  Virtual register %5 is not needed live through the block.
-
-# CHECK-LABEL: Bad machine code: LiveVariables: Block should not be in AliveBlocks
-# CHECK-NEXT:  - function:    testfloatslt
-# CHECK-NEXT:  - basic block: %bb.2 entry
-# CHECK-NEXT:  Virtual register %5 is not needed live through the block.
-# CHECK-NEXT:  LLVM ERROR: Found 3 machine code errors.
+# Bad machine code: LiveVariables: Block should not be in AliveBlocks
+# - function:    testfloatslt
+# - basic block: %bb.2 entry
+# Virtual register %5 is not needed live through the block.
+# LLVM ERROR: Found 3 machine code errors.
+#
+# Just verify that we do not crash (or get verifier error).
diff --git a/llvm/test/MachineVerifier/test_phis_precede_nonphis.mir b/llvm/test/MachineVerifier/test_phis_precede_nonphis.mir
--- a/llvm/test/MachineVerifier/test_phis_precede_nonphis.mir
+++ b/llvm/test/MachineVerifier/test_phis_precede_nonphis.mir
@@ -81,4 +81,8 @@
 # CHECK-NEXT:  - function:    broken
 # CHECK-NEXT:  - basic block: %bb.2 exit
 # CHECK-NEXT:  - instruction: %6:_(s8) = G_PHI %5:_(s8), %bb.0, %4:_(s8), %bb.1
+
+# CHECK-LABEL: Bad machine code: Virtual register defs don't dominate all uses.
+# CHECK-NEXT:  - function:    broken
+# CHECK-NEXT:  - v. register: %5
 # CHECK-NOT: Bad machine code