diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -566,17 +566,83 @@
   if (Inv == CxtI)
     return false;
 
-  // The context comes first, but they're both in the same block. Make sure
-  // there is nothing in between that might interrupt the control flow.
-  for (BasicBlock::const_iterator I =
-         std::next(BasicBlock::const_iterator(CxtI)), IE(Inv);
-       I != IE; ++I)
+  // The context comes first, but they're both in the same block.
+  // Make sure there is nothing in between that might interrupt
+  // the control flow, not even CxtI itself.
+  for (BasicBlock::const_iterator I(CxtI), IE(Inv); I != IE; ++I)
     if (!isGuaranteedToTransferExecutionToSuccessor(&*I))
       return false;
 
   return !isEphemeralValueOf(Inv, CxtI);
 }
 
+static bool isKnownNonZeroFromAssume(const Value *V, const Query &Q) {
+  // Use of assumptions is context-sensitive. If we don't have a context, we
+  // cannot use them!
+  if (!Q.AC || !Q.CxtI)
+    return false;
+
+  // Note that the patterns below need to be kept in sync with the code
+  // in AssumptionCache::updateAffectedValues.
+
+  auto CmpExcludesZero = [V](ICmpInst *Cmp) {
+    auto m_V = m_CombineOr(m_Specific(V), m_PtrToInt(m_Specific(V)));
+
+    Value *RHS;
+    CmpInst::Predicate Pred;
+    if (!match(Cmp, m_c_ICmp(Pred, m_V, m_Value(RHS))))
+      return false;
+    // Canonicalize 'v' to be on the LHS of the comparison.
+    if (Cmp->getOperand(1) != RHS)
+      Pred = CmpInst::getSwappedPredicate(Pred);
+
+    // assume(v u> y) -> assume(v != 0)
+    if (Pred == ICmpInst::ICMP_UGT)
+      return true;
+
+    // assume(v != 0)
+    // We special-case this one to ensure that we handle `assume(v != null)`.
+    if (Pred == ICmpInst::ICMP_NE)
+      return match(RHS, m_Zero());
+
+    // All other predicates - rely on generic ConstantRange handling.
+    ConstantInt *CI;
+    if (!match(RHS, m_ConstantInt(CI)))
+      return false;
+    ConstantRange RHSRange(CI->getValue());
+    ConstantRange TrueValues =
+        ConstantRange::makeAllowedICmpRegion(Pred, RHSRange);
+    return !TrueValues.contains(APInt::getNullValue(CI->getBitWidth()));
+  };
+
+  for (auto &AssumeVH : Q.AC->assumptionsFor(V)) {
+    if (!AssumeVH)
+      continue;
+    CallInst *I = cast<CallInst>(AssumeVH);
+    assert(I->getFunction() == Q.CxtI->getFunction() &&
+           "Got assumption for the wrong function!");
+    if (Q.isExcluded(I))
+      continue;
+
+    // Warning: This loop can end up being somewhat performance sensitive.
+    // We're running this loop for once for each value queried resulting in a
+    // runtime of ~O(#assumes * #values).
+
+    assert(I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume &&
+           "must be an assume intrinsic");
+
+    Value *Arg = I->getArgOperand(0);
+    ICmpInst *Cmp = dyn_cast<ICmpInst>(Arg);
+    if (!Cmp)
+      continue;
+
+    if (CmpExcludesZero(Cmp) && isValidAssumeForContext(I, Q.CxtI, Q.DT))
+      return true;
+  }
+
+  return false;
+}
+
 static void computeKnownBitsFromAssume(const Value *V, KnownBits &Known,
                                        unsigned Depth, const Query &Q) {
   // Use of assumptions is context-sensitive. If we don't have a context, we
@@ -2080,6 +2146,9 @@
     }
   }
 
+  if (isKnownNonZeroFromAssume(V, Q))
+    return true;
+
   // Some of the tests below are recursive, so bail out if we hit the limit.
   if (Depth++ >= MaxDepth)
     return false;
diff --git a/llvm/test/Transforms/InstCombine/assume.ll b/llvm/test/Transforms/InstCombine/assume.ll
--- a/llvm/test/Transforms/InstCombine/assume.ll
+++ b/llvm/test/Transforms/InstCombine/assume.ll
@@ -252,8 +252,7 @@
 ; CHECK-NEXT:    [[LOAD:%.*]] = load i32, i32* [[A:%.*]], align 4
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[LOAD]], 0
 ; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP]])
-; CHECK-NEXT:    [[RVAL:%.*]] = icmp eq i32 [[LOAD]], 0
-; CHECK-NEXT:    ret i1 [[RVAL]]
+; CHECK-NEXT:    ret i1 false
 ;
   %load = load i32, i32* %a
   %cmp = icmp ne i32 %load, 0
@@ -268,13 +267,12 @@
 define i1 @nonnull3(i32** %a, i1 %control) {
 ; CHECK-LABEL: @nonnull3(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[LOAD:%.*]] = load i32*, i32** [[A:%.*]], align 8
 ; CHECK-NEXT:    br i1 [[CONTROL:%.*]], label [[TAKEN:%.*]], label [[NOT_TAKEN:%.*]]
 ; CHECK:       taken:
+; CHECK-NEXT:    [[LOAD:%.*]] = load i32*, i32** [[A:%.*]], align 8
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32* [[LOAD]], null
 ; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP]])
-; CHECK-NEXT:    [[RVAL:%.*]] = icmp eq i32* [[LOAD]], null
-; CHECK-NEXT:    ret i1 [[RVAL]]
+; CHECK-NEXT:    ret i1 false
 ; CHECK:       not_taken:
 ; CHECK-NEXT:    ret i1 true
 ;
@@ -300,8 +298,7 @@
 ; CHECK-NEXT:    tail call void @escape(i32* [[LOAD]])
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32* [[LOAD]], null
 ; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP]])
-; CHECK-NEXT:    [[RVAL:%.*]] = icmp eq i32* [[LOAD]], null
-; CHECK-NEXT:    ret i1 [[RVAL]]
+; CHECK-NEXT:    ret i1 false
 ;
   %load = load i32*, i32** %a
   ;; This call may throw!
@@ -311,6 +308,23 @@
   %rval = icmp eq i32* %load, null
   ret i1 %rval
 }
+define i1 @nonnull5(i32** %a) {
+; CHECK-LABEL: @nonnull5(
+; CHECK-NEXT:    [[LOAD:%.*]] = load i32*, i32** [[A:%.*]], align 8
+; CHECK-NEXT:    tail call void @escape(i32* [[LOAD]])
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32* [[LOAD]], null
+; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP]])
+; CHECK-NEXT:    ret i1 false
+;
+  %load = load i32*, i32** %a
+  ;; This call may throw!
+  tail call void @escape(i32* %load)
+  %integral = ptrtoint i32* %load to i64
+  %cmp = icmp slt i64 %integral, 0
+  tail call void @llvm.assume(i1 %cmp) ; %load has at least highest bit set
+  %rval = icmp eq i32* %load, null
+  ret i1 %rval
+}
 
 ; PR35846 - https://bugs.llvm.org/show_bug.cgi?id=35846
 
@@ -336,12 +350,12 @@
 
 define void @debug_interference(i8 %x) {
 ; CHECK-LABEL: @debug_interference(
-; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq i8 [[X:%.*]], 0
-; CHECK-NEXT:    tail call void @llvm.dbg.value(metadata i32 5, metadata !7, metadata !DIExpression()), !dbg !9
-; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP1]])
-; CHECK-NEXT:    tail call void @llvm.dbg.value(metadata i32 5, metadata !7, metadata !DIExpression()), !dbg !9
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp ne i8 [[X:%.*]], 0
 ; CHECK-NEXT:    tail call void @llvm.dbg.value(metadata i32 5, metadata !7, metadata !DIExpression()), !dbg !9
 ; CHECK-NEXT:    tail call void @llvm.assume(i1 false)
+; CHECK-NEXT:    tail call void @llvm.dbg.value(metadata i32 5, metadata !7, metadata !DIExpression()), !dbg !9
+; CHECK-NEXT:    tail call void @llvm.dbg.value(metadata i32 5, metadata !7, metadata !DIExpression()), !dbg !9
+; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP2]])
 ; CHECK-NEXT:    ret void
 ;
   %cmp1 = icmp eq i8 %x, 0
diff --git a/llvm/test/Transforms/InstSimplify/assume-non-zero.ll b/llvm/test/Transforms/InstSimplify/assume-non-zero.ll
--- a/llvm/test/Transforms/InstSimplify/assume-non-zero.ll
+++ b/llvm/test/Transforms/InstSimplify/assume-non-zero.ll
@@ -10,8 +10,7 @@
 ; CHECK-LABEL: @nonnull0_true(
 ; CHECK-NEXT:    [[A:%.*]] = icmp ne i8* [[X:%.*]], null
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[A]])
-; CHECK-NEXT:    [[Q:%.*]] = icmp ne i8* [[X]], null
-; CHECK-NEXT:    ret i1 [[Q]]
+; CHECK-NEXT:    ret i1 true
 ;
   %a = icmp ne i8* %x, null
   call void @llvm.assume(i1 %a)
@@ -24,8 +23,7 @@
 ; CHECK-NEXT:    [[INTPTR:%.*]] = ptrtoint i8* [[X:%.*]] to i64
 ; CHECK-NEXT:    [[A:%.*]] = icmp ne i64 [[INTPTR]], 0
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[A]])
-; CHECK-NEXT:    [[Q:%.*]] = icmp ne i8* [[X]], null
-; CHECK-NEXT:    ret i1 [[Q]]
+; CHECK-NEXT:    ret i1 true
 ;
   %intptr = ptrtoint i8* %x to i64
   %a = icmp ne i64 %intptr, 0
@@ -38,14 +36,24 @@
 ; CHECK-LABEL: @nonnull2_true(
 ; CHECK-NEXT:    [[A:%.*]] = icmp ugt i8 [[X:%.*]], [[Y:%.*]]
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[A]])
-; CHECK-NEXT:    [[Q:%.*]] = icmp ne i8 [[X]], 0
-; CHECK-NEXT:    ret i1 [[Q]]
+; CHECK-NEXT:    ret i1 true
 ;
   %a = icmp ugt i8 %x, %y
   call void @llvm.assume(i1 %a)
   %q = icmp ne i8 %x, 0
   ret i1 %q
 }
+define i1 @nonnull2_true_swapped(i8 %x, i8 %y) {
+; CHECK-LABEL: @nonnull2_true_swapped(
+; CHECK-NEXT:    [[A:%.*]] = icmp ult i8 [[Y:%.*]], [[X:%.*]]
+; CHECK-NEXT:    call void @llvm.assume(i1 [[A]])
+; CHECK-NEXT:    ret i1 true
+;
+  %a = icmp ult i8 %y, %x
+  call void @llvm.assume(i1 %a)
+  %q = icmp ne i8 %x, 0
+  ret i1 %q
+}
 
 define i1 @nonnull3_unknown(i8 %x) {
 ; CHECK-LABEL: @nonnull3_unknown(
@@ -61,8 +69,7 @@
 ; CHECK-LABEL: @nonnull4_true(
 ; CHECK-NEXT:    [[A:%.*]] = icmp uge i8 [[X:%.*]], 1
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[A]])
-; CHECK-NEXT:    [[Q:%.*]] = icmp ne i8 [[X]], 0
-; CHECK-NEXT:    ret i1 [[Q]]
+; CHECK-NEXT:    ret i1 true
 ;
   %a = icmp uge i8 %x, 1
   call void @llvm.assume(i1 %a)
@@ -86,8 +93,7 @@
 ; CHECK-LABEL: @nonnull6_true(
 ; CHECK-NEXT:    [[A:%.*]] = icmp sgt i8 [[X:%.*]], 0
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[A]])
-; CHECK-NEXT:    [[Q:%.*]] = icmp ne i8 [[X]], 0
-; CHECK-NEXT:    ret i1 [[Q]]
+; CHECK-NEXT:    ret i1 true
 ;
   %a = icmp sgt i8 %x, 0
   call void @llvm.assume(i1 %a)
@@ -98,8 +104,7 @@
 ; CHECK-LABEL: @nonnull7_true(
 ; CHECK-NEXT:    [[A:%.*]] = icmp sgt i8 [[X:%.*]], 1
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[A]])
-; CHECK-NEXT:    [[Q:%.*]] = icmp ne i8 [[X]], 0
-; CHECK-NEXT:    ret i1 [[Q]]
+; CHECK-NEXT:    ret i1 true
 ;
   %a = icmp sgt i8 %x, 1
   call void @llvm.assume(i1 %a)
@@ -135,8 +140,7 @@
 ; CHECK-LABEL: @nonnull10_true(
 ; CHECK-NEXT:    [[A:%.*]] = icmp sge i8 [[X:%.*]], 1
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[A]])
-; CHECK-NEXT:    [[Q:%.*]] = icmp ne i8 [[X]], 0
-; CHECK-NEXT:    ret i1 [[Q]]
+; CHECK-NEXT:    ret i1 true
 ;
   %a = icmp sge i8 %x, 1
   call void @llvm.assume(i1 %a)