diff --git a/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
index 1f9b546ed2999..90e8c39e5a90d 100644
--- a/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
+++ b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
@@ -485,11 +485,36 @@ static bool allCallersPassValidPointerForArgument(
   });
 }
 
+// Try to prove that all Calls to F do not modify the memory pointed to by Arg,
+// using alias analysis local to each caller of F.
+static bool isArgUnmodifiedByAllCalls(Argument *Arg,
+                                      FunctionAnalysisManager &FAM) {
+  for (User *U : Arg->getParent()->users()) {
+
+    // Bail if we find an unexpected (non CallInst) use of the function.
+    auto *Call = dyn_cast<CallInst>(U);
+    if (!Call)
+      return false;
+
+    MemoryLocation Loc =
+        MemoryLocation::getForArgument(Call, Arg->getArgNo(), nullptr);
+
+    AAResults &AAR = FAM.getResult<AAManager>(*Call->getFunction());
+    // Bail as soon as we find a Call where Arg may be modified.
+    if (isModSet(AAR.getModRefInfo(Call, Loc)))
+      return false;
+  }
+
+  // All Users are Calls which do not modify the Arg.
+  return true;
+}
+
 /// Determine that this argument is safe to promote, and find the argument
 /// parts it can be promoted into.
 static bool findArgParts(Argument *Arg, const DataLayout &DL, AAResults &AAR,
                          unsigned MaxElements, bool IsRecursive,
-                         SmallVectorImpl<OffsetAndArgPart> &ArgPartsVec) {
+                         SmallVectorImpl<OffsetAndArgPart> &ArgPartsVec,
+                         FunctionAnalysisManager &FAM) {
   // Quick exit for unused arguments
   if (Arg->use_empty())
     return true;
@@ -716,10 +741,16 @@ static bool findArgParts(Argument *Arg, const DataLayout &DL, AAResults &AAR,
     return true;
 
   // Okay, now we know that the argument is only used by load instructions, and
-  // it is safe to unconditionally perform all of them. Use alias analysis to
-  // check to see if the pointer is guaranteed to not be modified from entry of
-  // the function to each of the load instructions.
+  // it is safe to unconditionally perform all of them.
+
+  // If we can determine that no call to the Function modifies the memory region
+  // accessed through Arg, through alias analysis using actual arguments in the
+  // callers, we know that it is guaranteed to be safe to promote the argument.
+  if (isArgUnmodifiedByAllCalls(Arg, FAM))
+    return true;
 
+  // Otherwise, use alias analysis to check if the pointer is guaranteed to not
+  // be modified from entry of the function to each of the load instructions.
   for (LoadInst *Load : Loads) {
     // Check to see if the load is invalidated from the start of the block to
     // the load itself.
@@ -846,7 +877,8 @@ static Function *promoteArguments(Function *F, FunctionAnalysisManager &FAM,
     // If we can promote the pointer to its value.
     SmallVector<OffsetAndArgPart, 4> ArgParts;
 
-    if (findArgParts(PtrArg, DL, AAR, MaxElements, IsRecursive, ArgParts)) {
+    if (findArgParts(PtrArg, DL, AAR, MaxElements, IsRecursive, ArgParts,
+                     FAM)) {
       SmallVector<Type *, 4> Types;
       for (const auto &Pair : ArgParts)
         Types.push_back(Pair.second.Ty);
diff --git a/llvm/test/Transforms/ArgumentPromotion/actual-arguments.ll b/llvm/test/Transforms/ArgumentPromotion/actual-arguments.ll
index 63366ba998c7b..ca757a165fa4b 100644
--- a/llvm/test/Transforms/ArgumentPromotion/actual-arguments.ll
+++ b/llvm/test/Transforms/ArgumentPromotion/actual-arguments.ll
@@ -68,18 +68,14 @@ define internal i32 @test_cannot_promote_3(ptr %p, ptr nocapture readonly %test_
   ret i32 %sum
 }
 
-; FIXME: We should perform ArgPromotion here!
-;
 ; This is called only by @caller_safe_args_1, from which we can prove that
 ; %test_c does not alias %p for any Call to the function, so we can promote it.
 ;
 define internal i32 @test_can_promote_1(ptr %p, ptr nocapture readonly %test_c) {
 ; CHECK-LABEL: define {{[^@]+}}@test_can_promote_1
-; CHECK-SAME: (ptr [[P:%.*]], ptr nocapture readonly [[TEST_C:%.*]]) {
-; CHECK-NEXT:    [[TEST_C_VAL:%.*]] = load i32, ptr [[TEST_C]], align 4
-; CHECK-NEXT:    [[RES:%.*]] = call i32 @callee(ptr [[P]], i32 [[TEST_C_VAL]])
-; CHECK-NEXT:    [[LTEST_C:%.*]] = load i32, ptr [[TEST_C]], align 4
-; CHECK-NEXT:    [[SUM:%.*]] = add i32 [[LTEST_C]], [[RES]]
+; CHECK-SAME: (ptr [[P:%.*]], i32 [[TEST_C_0_VAL:%.*]]) {
+; CHECK-NEXT:    [[RES:%.*]] = call i32 @callee(ptr [[P]], i32 [[TEST_C_0_VAL]])
+; CHECK-NEXT:    [[SUM:%.*]] = add i32 [[TEST_C_0_VAL]], [[RES]]
 ; CHECK-NEXT:    ret i32 [[SUM]]
 ;
   %res = call i32 @callee(ptr %p, ptr %test_c)
@@ -91,19 +87,15 @@ define internal i32 @test_can_promote_1(ptr %p, ptr nocapture readonly %test_c)
   ret i32 %sum
 }
 
-; FIXME: We should perform ArgPromotion here!
-;
 ; This is called by multiple callers (@caller_safe_args_1, @caller_safe_args_2),
 ; from which we can prove that %test_c does not alias %p for any Call to the
 ; function, so we can promote it.
 ;
 define internal i32 @test_can_promote_2(ptr %p, ptr nocapture readonly %test_c) {
 ; CHECK-LABEL: define {{[^@]+}}@test_can_promote_2
-; CHECK-SAME: (ptr [[P:%.*]], ptr nocapture readonly [[TEST_C:%.*]]) {
-; CHECK-NEXT:    [[TEST_C_VAL:%.*]] = load i32, ptr [[TEST_C]], align 4
-; CHECK-NEXT:    [[RES:%.*]] = call i32 @callee(ptr [[P]], i32 [[TEST_C_VAL]])
-; CHECK-NEXT:    [[LTEST_C:%.*]] = load i32, ptr [[TEST_C]], align 4
-; CHECK-NEXT:    [[SUM:%.*]] = add i32 [[LTEST_C]], [[RES]]
+; CHECK-SAME: (ptr [[P:%.*]], i32 [[TEST_C_0_VAL:%.*]]) {
+; CHECK-NEXT:    [[RES:%.*]] = call i32 @callee(ptr [[P]], i32 [[TEST_C_0_VAL]])
+; CHECK-NEXT:    [[SUM:%.*]] = add i32 [[TEST_C_0_VAL]], [[RES]]
 ; CHECK-NEXT:    ret i32 [[SUM]]
 ;
   %res = call i32 @callee(ptr %p, ptr %test_c)
@@ -186,8 +178,10 @@ define i32 @caller_safe_args_1(i64 %n) {
 ; CHECK-NEXT:    [[CALLER_C:%.*]] = alloca i32, align 4
 ; CHECK-NEXT:    store i32 5, ptr [[CALLER_C]], align 4
 ; CHECK-NEXT:    [[RES1:%.*]] = call i32 @test_cannot_promote_3(ptr [[P]], ptr [[CALLER_C]])
-; CHECK-NEXT:    [[RES2:%.*]] = call i32 @test_can_promote_1(ptr [[P]], ptr [[CALLER_C]])
-; CHECK-NEXT:    [[RES3:%.*]] = call i32 @test_can_promote_2(ptr [[P]], ptr [[CALLER_C]])
+; CHECK-NEXT:    [[CALLER_C_VAL:%.*]] = load i32, ptr [[CALLER_C]], align 4
+; CHECK-NEXT:    [[RES2:%.*]] = call i32 @test_can_promote_1(ptr [[P]], i32 [[CALLER_C_VAL]])
+; CHECK-NEXT:    [[CALLER_C_VAL1:%.*]] = load i32, ptr [[CALLER_C]], align 4
+; CHECK-NEXT:    [[RES3:%.*]] = call i32 @test_can_promote_2(ptr [[P]], i32 [[CALLER_C_VAL1]])
 ; CHECK-NEXT:    [[RES12:%.*]] = add i32 [[RES1]], [[RES2]]
 ; CHECK-NEXT:    [[RES:%.*]] = add i32 [[RES12]], [[RES3]]
 ; CHECK-NEXT:    ret i32 [[RES]]
@@ -215,7 +209,8 @@ define i32 @caller_safe_args_2(i64 %n, ptr %p) {
 ; CHECK-NEXT:    call void @memset(ptr [[P]], i64 0, i64 [[N]])
 ; CHECK-NEXT:    [[CALLER_C:%.*]] = alloca i32, align 4
 ; CHECK-NEXT:    store i32 5, ptr [[CALLER_C]], align 4
-; CHECK-NEXT:    [[RES:%.*]] = call i32 @test_can_promote_2(ptr [[P]], ptr [[CALLER_C]])
+; CHECK-NEXT:    [[CALLER_C_VAL:%.*]] = load i32, ptr [[CALLER_C]], align 4
+; CHECK-NEXT:    [[RES:%.*]] = call i32 @test_can_promote_2(ptr [[P]], i32 [[CALLER_C_VAL]])
 ; CHECK-NEXT:    ret i32 [[RES]]
 ;
   call void @memset(ptr %p, i64 0, i64 %n)