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
@@ -1923,10 +1923,13 @@
       // We no longer need the assumes or the type test.
       for (auto Assume : Assumes)
         Assume->eraseFromParent();
+      // We may run into multiple type tests feeding into a phi. In that case
+      // RAUW true and leave the assume.
+      if (!CI->use_empty())
+        CI->replaceAllUsesWith(ConstantInt::getTrue(M.getContext()));
       // We can't use RecursivelyDeleteTriviallyDeadInstructions here because we
       // may use the vtable argument later.
-      if (CI->use_empty())
-        CI->eraseFromParent();
+      CI->eraseFromParent();
     };
 
     // At this point we could remove all type test assume sequences, as they
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 +1,46 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -passes=wholeprogramdevirt -whole-program-visibility %s 2>&1 | FileCheck %s
+
+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:    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:    br label [[FIN]]
+; CHECK:       fin:
+; CHECK-NEXT:    [[PN:%.*]] = phi i1 [ true, [[BB1]] ], [ true, [[BB2]] ]
+; CHECK-NEXT:    call void @llvm.assume(i1 [[PN]])
+; 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
+}
+
+declare i1 @llvm.type.test(ptr, metadata)
+declare void @llvm.assume(i1)
+
+!0 = !{i32 0, !"typeid"}