diff --git a/llvm/lib/Analysis/TypeMetadataUtils.cpp b/llvm/lib/Analysis/TypeMetadataUtils.cpp
--- a/llvm/lib/Analysis/TypeMetadataUtils.cpp
+++ b/llvm/lib/Analysis/TypeMetadataUtils.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Analysis/TypeMetadataUtils.h"
+#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/IR/Instructions.h"
@@ -80,9 +81,23 @@
   const Module *M = CI->getParent()->getParent()->getParent();
 
   // Find llvm.assume intrinsics for this llvm.type.test call.
+  // Look through phis as multiple type tests may have been merged to feed into
+  // the same assume. We need to make sure to handle recursive phis.
+  SmallPtrSet<Value *, 2> Visited;
+  SmallVector<Value *, 2> Worklist;
   for (const Use &CIU : CI->uses())
-    if (auto *Assume = dyn_cast<AssumeInst>(CIU.getUser()))
+    Worklist.push_back(CIU.getUser());
+  while (!Worklist.empty()) {
+    Value *V = Worklist.pop_back_val();
+    if (!Visited.insert(V).second)
+      continue;
+    if (auto *Assume = dyn_cast<AssumeInst>(V)) {
       Assumes.push_back(Assume);
+    } else if (auto *Phi = dyn_cast<PHINode>(V)) {
+      for (const Use &PIU : Phi->uses())
+        Worklist.push_back(PIU.getUser());
+    }
+  }
 
   // If we found any, search for virtual calls based on %p and add them to
   // DevirtCalls.
diff --git a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
--- a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
+++ b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
@@ -56,6 +56,7 @@
 #include "llvm/ADT/DenseMapInfo.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/MapVector.h"
+#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/Triple.h"
@@ -1896,6 +1897,8 @@
   // points to a member of the type identifier %md. Group calls by (type ID,
   // offset) pair (effectively the identity of the virtual function) and store
   // to CallSlots.
+
+  SmallPtrSet<Instruction *, 4> DeletedAssumes;
   for (Use &U : llvm::make_early_inc_range(TypeTestFunc->uses())) {
     auto *CI = dyn_cast<CallInst>(U.getUser());
     if (!CI)
@@ -1918,8 +1921,10 @@
 
     auto RemoveTypeTestAssumes = [&]() {
       // We no longer need the assumes or the type test.
-      for (auto Assume : Assumes)
-        Assume->eraseFromParent();
+      for (auto *Assume : Assumes) {
+        if (DeletedAssumes.insert(Assume).second)
+          Assume->eraseFromParent();
+      }
       // We can't use RecursivelyDeleteTriviallyDeadInstructions here because we
       // may use the vtable argument later.
       if (CI->use_empty())
diff --git a/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl-assume-phi.ll b/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl-assume-phi.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl-assume-phi.ll
@@ -0,0 +1,83 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -passes=wholeprogramdevirt -whole-program-visibility %s 2>&1 | FileCheck %s
+
+; Check that the assume in assume(phi(typetest1, typetest2)) is removed by WPD.
+define void @call(ptr %obj, i1 %i) {
+; CHECK-LABEL: @call(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[I:%.*]], label [[BB1:%.*]], label [[BB2:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    [[VTABLE:%.*]] = load ptr, ptr [[OBJ:%.*]], align 8
+; CHECK-NEXT:    [[FPTR:%.*]] = load ptr, ptr [[VTABLE]], align 8
+; CHECK-NEXT:    call void [[FPTR]](ptr [[OBJ]])
+; CHECK-NEXT:    [[P:%.*]] = call i1 @llvm.type.test(ptr [[VTABLE]], metadata !"typeid")
+; CHECK-NEXT:    br label [[FIN:%.*]]
+; CHECK:       bb2:
+; CHECK-NEXT:    [[VTABLE2:%.*]] = load ptr, ptr [[OBJ]], align 8
+; CHECK-NEXT:    [[FPTR2:%.*]] = load ptr, ptr [[VTABLE2]], align 8
+; CHECK-NEXT:    call void [[FPTR2]](ptr [[OBJ]])
+; CHECK-NEXT:    [[P2:%.*]] = call i1 @llvm.type.test(ptr [[VTABLE2]], metadata !"typeid")
+; CHECK-NEXT:    br label [[FIN]]
+; CHECK:       fin:
+; CHECK-NEXT:    [[PN:%.*]] = phi i1 [ [[P]], [[BB1]] ], [ [[P2]], [[BB2]] ]
+; CHECK-NEXT:    ret void
+;
+entry:
+  br i1 %i, label %bb1, label %bb2
+bb1:
+  %vtable = load ptr, ptr %obj
+  %fptr = load ptr, ptr %vtable
+  call void %fptr(ptr %obj)
+  %p = call i1 @llvm.type.test(ptr %vtable, metadata !"typeid")
+  br label %fin
+bb2:
+  %vtable2 = load ptr, ptr %obj
+  %fptr2 = load ptr, ptr %vtable2
+  call void %fptr2(ptr %obj)
+  %p2 = call i1 @llvm.type.test(ptr %vtable2, metadata !"typeid")
+  br label %fin
+fin:
+  %pn = phi i1 [ %p, %bb1 ], [ %p2, %bb2 ]
+  call void @llvm.assume(i1 %pn)
+  ret void
+}
+
+; Check that we handle phi cycles.
+define void @call2(ptr %obj, i1 %i) {
+; CHECK-LABEL: @call2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[BB1:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    [[Z:%.*]] = phi i1 [ false, [[ENTRY:%.*]] ], [ [[P:%.*]], [[BB1]] ], [ [[PN:%.*]], [[BB2:%.*]] ]
+; CHECK-NEXT:    [[VTABLE:%.*]] = load ptr, ptr [[OBJ:%.*]], align 8
+; CHECK-NEXT:    [[FPTR:%.*]] = load ptr, ptr [[VTABLE]], align 8
+; CHECK-NEXT:    call void [[FPTR]](ptr [[OBJ]])
+; CHECK-NEXT:    [[P]] = call i1 @llvm.type.test(ptr [[VTABLE]], metadata !"typeid")
+; CHECK-NEXT:    br i1 [[I:%.*]], label [[BB2]], label [[BB1]]
+; CHECK:       bb2:
+; CHECK-NEXT:    [[PN]] = phi i1 [ [[Z]], [[BB1]] ]
+; CHECK-NEXT:    br i1 [[I]], label [[FIN:%.*]], label [[BB1]]
+; CHECK:       fin:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %bb1
+bb1:
+  %z = phi i1 [ false, %entry ], [ %p, %bb1 ], [ %pn, %bb2 ]
+  %vtable = load ptr, ptr %obj
+  %fptr = load ptr, ptr %vtable
+  call void %fptr(ptr %obj)
+  %p = call i1 @llvm.type.test(ptr %vtable, metadata !"typeid")
+  br i1 %i, label %bb2, label %bb1
+bb2:
+  %pn = phi i1 [ %z, %bb1 ]
+  br i1 %i, label %fin, label %bb1
+fin:
+  call void @llvm.assume(i1 %pn)
+  ret void
+}
+
+declare i1 @llvm.type.test(ptr, metadata)
+declare void @llvm.assume(i1)
+
+!0 = !{i32 0, !"typeid"}