diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -3115,7 +3115,8 @@
 /// beginning of DestBlock, which can only happen if it's safe to move the
 /// instruction past all of the instructions between it and the end of its
 /// block.
-static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
+static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock,
+                                 InstCombiner::BuilderTy &Builder) {
   assert(I->hasOneUse() && "Invariants didn't hold!");
   BasicBlock *SrcBlock = I->getParent();
 
@@ -3149,6 +3150,24 @@
       if (Scan->mayWriteToMemory())
         return false;
   }
+
+  // If this instruction was providing nonnull guarantees insert assumptions for
+  // nonnull call site arguments.
+  if (auto CS = dyn_cast<CallBase>(I)) {
+    for (unsigned Idx = 0; Idx != CS->getNumArgOperands(); Idx++)
+      if (CS->paramHasAttr(Idx, Attribute::NonNull) ||
+          (CS->paramHasAttr(Idx, Attribute::Dereferenceable) &&
+           !llvm::NullPointerIsDefined(CS->getFunction(),
+                                       CS->getArgOperand(Idx)
+                                           ->getType()
+                                           ->getPointerAddressSpace()))) {
+        Value *V = CS->getArgOperand(Idx);
+
+        Builder.SetInsertPoint(I->getParent(), I->getIterator());
+        Builder.CreateAssumption(Builder.CreateIsNotNull(V));
+      }
+  }
+
   BasicBlock::iterator InsertPos = DestBlock->getFirstInsertionPt();
   I->moveBefore(&*InsertPos);
   ++NumSunkInst;
@@ -3283,7 +3302,7 @@
         // otherwise), we can keep going.
         if (UserIsSuccessor && UserParent->getUniquePredecessor()) {
           // Okay, the CFG is simple enough, try to sink this instruction.
-          if (TryToSinkInstruction(I, UserParent)) {
+          if (TryToSinkInstruction(I, UserParent, Builder)) {
             LLVM_DEBUG(dbgs() << "IC: Sink: " << *I << '\n');
             MadeIRChange = true;
             // We'll add uses of the sunk instruction below, but since sinking
diff --git a/llvm/test/Transforms/InstCombine/assume-replacing-call.ll b/llvm/test/Transforms/InstCombine/assume-replacing-call.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/assume-replacing-call.ll
@@ -0,0 +1,192 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instcombine -S | FileCheck %s
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i32 @test_sink_replacement1(i8* %p) {
+; CHECK-LABEL: @test_sink_replacement1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp ne i8* [[P:%.*]], null
+; CHECK-NEXT:    call void @llvm.assume(i1 [[TMP0]])
+; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i8* [[P]], null
+; CHECK-NEXT:    br i1 [[TOBOOL]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
+; CHECK:       if.then:
+; CHECK-NEXT:    br label [[CLEANUP:%.*]]
+; CHECK:       if.end:
+; CHECK-NEXT:    [[CALL:%.*]] = call i64 @func_test(i8* nonnull [[P]]) #2
+; CHECK-NEXT:    [[CONV:%.*]] = trunc i64 [[CALL]] to i32
+; CHECK-NEXT:    br label [[CLEANUP]]
+; CHECK:       cleanup:
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ [[CONV]], [[IF_END]] ], [ -1, [[IF_THEN]] ]
+; CHECK-NEXT:    ret i32 [[RETVAL_0]]
+;
+entry:
+  %call = call i64 @func_test(i8* nonnull %p) #2
+  %conv = trunc i64 %call to i32
+  %tobool = icmp ne i8* %p, null
+  br i1 %tobool, label %if.end, label %if.then
+
+if.then:
+  br label %cleanup
+
+if.end:
+  br label %cleanup
+
+cleanup:
+  %retval.0 = phi i32 [ %conv, %if.end ], [ -1, %if.then ]
+  ret i32 %retval.0
+}
+
+define i32 @test_sink_replacement2(i8* %p) {
+; CHECK-LABEL: @test_sink_replacement2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp ne i8* [[P:%.*]], null
+; CHECK-NEXT:    call void @llvm.assume(i1 [[TMP0]])
+; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i8* [[P]], null
+; CHECK-NEXT:    br i1 [[TOBOOL]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
+; CHECK:       if.then:
+; CHECK-NEXT:    br label [[CLEANUP:%.*]]
+; CHECK:       if.end:
+; CHECK-NEXT:    [[CALL:%.*]] = call i64 @func_test(i8* nonnull dereferenceable(1) [[P]]) #2
+; CHECK-NEXT:    [[CONV:%.*]] = trunc i64 [[CALL]] to i32
+; CHECK-NEXT:    br label [[CLEANUP]]
+; CHECK:       cleanup:
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ [[CONV]], [[IF_END]] ], [ -1, [[IF_THEN]] ]
+; CHECK-NEXT:    ret i32 [[RETVAL_0]]
+;
+entry:
+  %call = call i64 @func_test(i8* dereferenceable(1) %p) #2
+  %conv = trunc i64 %call to i32
+  %tobool = icmp ne i8* %p, null
+  br i1 %tobool, label %if.end, label %if.then
+
+if.then:
+  br label %cleanup
+
+if.end:
+  br label %cleanup
+
+cleanup:
+  %retval.0 = phi i32 [ %conv, %if.end ], [ -1, %if.then ]
+  ret i32 %retval.0
+}
+
+define i32 @test_sink_replacement3(i8* %p) {
+; CHECK-LABEL: @test_sink_replacement3(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp ne i8* [[P:%.*]], null
+; CHECK-NEXT:    call void @llvm.assume(i1 [[TMP0]])
+; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i8* [[P]], null
+; CHECK-NEXT:    br i1 [[TOBOOL]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
+; CHECK:       if.then:
+; CHECK-NEXT:    br label [[CLEANUP:%.*]]
+; CHECK:       if.end:
+; CHECK-NEXT:    [[CALL:%.*]] = call i64 @func_test_nonnull(i8* [[P]]) #2
+; CHECK-NEXT:    [[CONV:%.*]] = trunc i64 [[CALL]] to i32
+; CHECK-NEXT:    br label [[CLEANUP]]
+; CHECK:       cleanup:
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ [[CONV]], [[IF_END]] ], [ -1, [[IF_THEN]] ]
+; CHECK-NEXT:    ret i32 [[RETVAL_0]]
+;
+entry:
+  %call = call i64 @func_test_nonnull(i8* %p) #2
+  %conv = trunc i64 %call to i32
+  %tobool = icmp ne i8* %p, null
+  br i1 %tobool, label %if.end, label %if.then
+
+if.then:
+  br label %cleanup
+
+if.end:
+  br label %cleanup
+
+cleanup:
+  %retval.0 = phi i32 [ %conv, %if.end ], [ -1, %if.then ]
+  ret i32 %retval.0
+}
+
+define i32 @test_sink_replacement4(i8* %p) {
+; CHECK-LABEL: @test_sink_replacement4(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[A:%.*]]
+; CHECK:       a:
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp ne i8* [[P:%.*]], null
+; CHECK-NEXT:    call void @llvm.assume(i1 [[TMP0]])
+; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i8* [[P]], null
+; CHECK-NEXT:    br i1 [[TOBOOL]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
+; CHECK:       if.then:
+; CHECK-NEXT:    br label [[CLEANUP:%.*]]
+; CHECK:       if.end:
+; CHECK-NEXT:    [[CALL:%.*]] = call i64 @func_test(i8* nonnull dereferenceable(1) [[P]]) #2
+; CHECK-NEXT:    [[CONV:%.*]] = trunc i64 [[CALL]] to i32
+; CHECK-NEXT:    br label [[CLEANUP]]
+; CHECK:       cleanup:
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ [[CONV]], [[IF_END]] ], [ -1, [[IF_THEN]] ]
+; CHECK-NEXT:    ret i32 [[RETVAL_0]]
+;
+entry:
+  br label %a
+a:
+  %call = call i64 @func_test(i8* dereferenceable(1) %p) #2
+  %conv = trunc i64 %call to i32
+  %tobool = icmp ne i8* %p, null
+  br i1 %tobool, label %if.end, label %if.then
+
+if.then:
+  br label %cleanup
+
+if.end:
+  br label %cleanup
+
+cleanup:
+  %retval.0 = phi i32 [ %conv, %if.end ], [ -1, %if.then ]
+  ret i32 %retval.0
+}
+
+define i32 @test_sink_replacement5(i64 %i) {
+; CHECK-LABEL: @test_sink_replacement5(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[P:%.*]] = inttoptr i64 [[I:%.*]] to i8*
+; CHECK-NEXT:    br label [[A:%.*]]
+; CHECK:       a:
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp ne i64 [[I]], 0
+; CHECK-NEXT:    call void @llvm.assume(i1 [[TMP0]])
+; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i64 [[I]], 0
+; CHECK-NEXT:    br i1 [[TOBOOL]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
+; CHECK:       if.then:
+; CHECK-NEXT:    br label [[CLEANUP:%.*]]
+; CHECK:       if.end:
+; CHECK-NEXT:    [[CALL:%.*]] = call i64 @func_test(i8* nonnull dereferenceable(1) [[P]]) #2
+; CHECK-NEXT:    [[CONV:%.*]] = trunc i64 [[CALL]] to i32
+; CHECK-NEXT:    br label [[CLEANUP]]
+; CHECK:       cleanup:
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ [[CONV]], [[IF_END]] ], [ -1, [[IF_THEN]] ]
+; CHECK-NEXT:    ret i32 [[RETVAL_0]]
+;
+entry:
+  %p = inttoptr i64 %i to i8*
+  br label %a
+a:
+  %call = call i64 @func_test(i8* dereferenceable(1) %p) #2
+  %conv = trunc i64 %call to i32
+  %tobool = icmp ne i8* %p, null
+  br i1 %tobool, label %if.end, label %if.then
+
+if.then:
+  br label %cleanup
+
+if.end:
+  br label %cleanup
+
+cleanup:
+  %retval.0 = phi i32 [ %conv, %if.end ], [ -1, %if.then ]
+  ret i32 %retval.0
+}
+
+declare i64 @func_test(i8* %0) #1
+
+declare i64 @func_test_nonnull(i8* nonnull %0) #3
+
+attributes #1 = { readonly }
+attributes #2 = { nounwind }
+attributes #3 = { readonly }