diff --git a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp b/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
--- a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
+++ b/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
@@ -20,6 +20,7 @@
 #include "llvm/ADT/EquivalenceClasses.h"
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/StringRef.h"
@@ -1820,6 +1821,15 @@
   Old->replaceUsesWithIf(New, isDirectCall);
 }
 
+// Returns if the Value is only used by assumes, permitting indirectly via phis.
+static bool hasOnlyAssumeUsers(Value *V, SmallPtrSet<Value *, 2> &Visited) {
+  return all_of(V->uses(), [&Visited](Use &U) {
+    if (auto *P = dyn_cast<PHINode>(U.getUser()))
+      return !Visited.insert(P).second || hasOnlyAssumeUsers(P, Visited);
+    return isa<AssumeInst>(U.getUser());
+  });
+}
+
 bool LowerTypeTestsModule::lower() {
   Function *TypeTestFunc =
       M.getFunction(Intrinsic::getName(Intrinsic::type_test));
@@ -2101,14 +2111,8 @@
       // lower it here. We also don't want to rewrite any associated globals
       // unnecessarily. These will be removed by a subsequent LTT invocation
       // with the DropTypeTests flag set.
-      bool OnlyAssumeUses = !CI->use_empty();
-      for (const Use &CIU : CI->uses()) {
-        if (isa<AssumeInst>(CIU.getUser()))
-          continue;
-        OnlyAssumeUses = false;
-        break;
-      }
-      if (OnlyAssumeUses)
+      SmallPtrSet<Value *, 2> Visited;
+      if (hasOnlyAssumeUsers(CI, Visited))
         continue;
 
       auto TypeIdMDVal = dyn_cast<MetadataAsValue>(CI->getArgOperand(1));
diff --git a/llvm/test/Transforms/LowerTypeTests/assume-phi.ll b/llvm/test/Transforms/LowerTypeTests/assume-phi.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/LowerTypeTests/assume-phi.ll
@@ -0,0 +1,85 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -passes=lowertypetests -whole-program-visibility %s 2>&1 | FileCheck %s
+
+; Make sure to skip type tests that feed into assumes perhaps indirectly via phis.
+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:    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
+}
+
+; Make sure 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:    call void @llvm.assume(i1 [[PN]])
+; 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"}
diff --git a/llvm/test/Transforms/LowerTypeTests/blockaddress-2.ll b/llvm/test/Transforms/LowerTypeTests/blockaddress-2.ll
--- a/llvm/test/Transforms/LowerTypeTests/blockaddress-2.ll
+++ b/llvm/test/Transforms/LowerTypeTests/blockaddress-2.ll
@@ -16,8 +16,11 @@
   ret void
 }
 
+declare void @use(i1)
+
 define internal fastcc void @do_f() unnamed_addr !type !2 {
   %1 = tail call i1 @llvm.type.test(i8* undef, metadata !"_ZTSFiP4fileP3uioP5ucrediP6threadE"), !nosanitize !3
+  call void @use(i1 %1)
   ret void
 }
 
diff --git a/llvm/test/Transforms/LowerTypeTests/blockaddress.ll b/llvm/test/Transforms/LowerTypeTests/blockaddress.ll
--- a/llvm/test/Transforms/LowerTypeTests/blockaddress.ll
+++ b/llvm/test/Transforms/LowerTypeTests/blockaddress.ll
@@ -9,9 +9,12 @@
 
 target triple = "x86_64-unknown-linux"
 
+declare void @use(i1)
+
 define void @f1() {
 entry:
   %0 = call i1 @llvm.type.test(i8* bitcast (i8* ()* @f2 to i8*), metadata !"_ZTSFvP3bioE")
+  call void @use(i1 %0)
   ret void
 }
 
diff --git a/llvm/test/Transforms/LowerTypeTests/cfi-direct-call1.ll b/llvm/test/Transforms/LowerTypeTests/cfi-direct-call1.ll
--- a/llvm/test/Transforms/LowerTypeTests/cfi-direct-call1.ll
+++ b/llvm/test/Transforms/LowerTypeTests/cfi-direct-call1.ll
@@ -21,6 +21,7 @@
 declare !type !3 !type !4 extern_weak i32 @extern_weak()
 declare !type !3 !type !4 i32 @extern_decl()
 declare i1 @llvm.type.test(i8*, metadata)
+declare void @use(i1)
 
 define hidden i32 @main(i32 %argc) {
 entry:
@@ -29,10 +30,12 @@
   %fptr2 = select i1 %cmp.i, i32 ()* @extern_weak, i32 ()* @extern_decl
   %0 = bitcast i32 ()* %fptr1 to i8*
   %1 = tail call i1 @llvm.type.test(i8* nonnull %0, metadata !"_ZTSFivE")
+  call void @use(i1 %1)
 
   %call2 = tail call i32 %fptr1()
   %2 = bitcast i32 ()* %fptr2 to i8*
   %3 = tail call i1 @llvm.type.test(i8* %2, metadata !"_ZTSFivE")
+  call void @use(i1 %3)
 
   %call4 = tail call i32 %fptr2()
   %call5 = tail call i32 @extern_decl()
diff --git a/llvm/test/Transforms/LowerTypeTests/layout.ll b/llvm/test/Transforms/LowerTypeTests/layout.ll
--- a/llvm/test/Transforms/LowerTypeTests/layout.ll
+++ b/llvm/test/Transforms/LowerTypeTests/layout.ll
@@ -18,10 +18,14 @@
 !2 = !{i32 0, !"typeid3"}
 
 declare i1 @llvm.type.test(i8* %ptr, metadata %bitset) nounwind readnone
+declare void @use(i1)
 
 define void @foo() {
   %x = call i1 @llvm.type.test(i8* undef, metadata !"typeid1")
+  call void @use(i1 %x)
   %y = call i1 @llvm.type.test(i8* undef, metadata !"typeid2")
+  call void @use(i1 %y)
   %z = call i1 @llvm.type.test(i8* undef, metadata !"typeid3")
+  call void @use(i1 %z)
   ret void
 }
diff --git a/llvm/test/Transforms/LowerTypeTests/simple.ll b/llvm/test/Transforms/LowerTypeTests/simple.ll
--- a/llvm/test/Transforms/LowerTypeTests/simple.ll
+++ b/llvm/test/Transforms/LowerTypeTests/simple.ll
@@ -44,6 +44,7 @@
 ; CHECK: @bits.{{[0-9]*}} = private alias i8, getelementptr inbounds ([68 x i8], [68 x i8]* [[BA]], i32 0, i32 0)
 
 declare i1 @llvm.type.test(i8* %ptr, metadata %bitset) nounwind readnone
+declare void @use(i1)
 
 ; CHECK: @foo(i32* [[A0:%[^ ]*]])
 define i1 @foo(i32* %p) {
@@ -66,9 +67,11 @@
 
   ; CHECK: [[R16:%[^ ]*]] = phi i1 [ false, {{%[^ ]*}} ], [ [[R11]], {{%[^ ]*}} ]
   %x = call i1 @llvm.type.test(i8* %pi8, metadata !"typeid1")
+  call void @use(i1 %x)
 
   ; CHECK-NOT: llvm.type.test
   %y = call i1 @llvm.type.test(i8* %pi8, metadata !"typeid1")
+  call void @use(i1 %y)
 
   ; CHECK: ret i1 [[R16]]
   ret i1 %x
@@ -85,6 +88,7 @@
   ; CHECK: [[S5:%[^ ]*]] = or i32 [[S3]], [[S4]]
   ; CHECK: [[S6:%[^ ]*]] = icmp ule i32 [[S5]], 1
   %x = call i1 @llvm.type.test(i8* %pi8, metadata !"typeid2")
+  call void @use(i1 %x)
 
   ; CHECK: ret i1 [[S6]]
   ret i1 %x