diff --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -1990,12 +1990,13 @@
     return true;
   }
 
+  bool Changed = false;
+
   // If the global is never loaded (but may be stored to), it is dead.
   // Delete it now.
   if (!GS.IsLoaded) {
     LLVM_DEBUG(dbgs() << "GLOBAL NEVER LOADED: " << *GV << "\n");
 
-    bool Changed;
     if (isLeakCheckerRoot(GV)) {
       // Delete any constant stores to the global.
       Changed = CleanupPointerRootUsers(GV, GetTLI);
@@ -2021,11 +2022,14 @@
     // Don't actually mark a global constant if it's atomic because atomic loads
     // are implemented by a trivial cmpxchg in some edge-cases and that usually
     // requires write access to the variable even if it's not actually changed.
-    if (GS.Ordering == AtomicOrdering::NotAtomic)
+    if (GS.Ordering == AtomicOrdering::NotAtomic) {
+      assert(!GV->isConstant() && "Expected a non-constant global");
       GV->setConstant(true);
+      Changed = true;
+    }
 
     // Clean up any obviously simplifiable users now.
-    CleanupConstantGlobalUsers(GV, GV->getInitializer(), DL, GetTLI);
+    Changed |= CleanupConstantGlobalUsers(GV, GV->getInitializer(), DL, GetTLI);
 
     // If the global is dead now, just nuke it.
     if (GV->use_empty()) {
@@ -2085,7 +2089,7 @@
     }
   }
 
-  return false;
+  return Changed;
 }
 
 /// Analyze the specified global variable and optimize it if possible.  If we
diff --git a/llvm/test/Transforms/GlobalOpt/const-return-status-atomic.ll b/llvm/test/Transforms/GlobalOpt/const-return-status-atomic.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/GlobalOpt/const-return-status-atomic.ll
@@ -0,0 +1,27 @@
+; RUN: opt -globalopt < %s -S -o - | FileCheck %s
+
+; When simplifying users of a global variable, the pass could incorrectly
+; return false if there were still some uses left, and no further optimizations
+; was done. This was caught by the pass return status check that is hidden
+; under EXPENSIVE_CHECKS.
+
+@GV1 = internal unnamed_addr global i64 1, align 8
+
+; CHECK: @GV1 = internal unnamed_addr global i64 1, align 8
+
+define void @test1() local_unnamed_addr {
+; CHECK-LABEL: @test1
+; CHECK-NEXT: %val = load atomic i8
+; CHECK-NEXT: ret void
+
+  %val = load atomic i8, i8* bitcast (i64* @GV1 to i8*) acquire, align 8
+  ret void
+}
+
+define i64 @test2() local_unnamed_addr {
+; CHECK-LABEL: @test2
+; CHECK-NEXT: ret i64 1
+
+  %val = load atomic i64, i64* @GV1 acquire, align 8
+  ret i64 %val
+}
diff --git a/llvm/test/Transforms/GlobalOpt/const-return-status.ll b/llvm/test/Transforms/GlobalOpt/const-return-status.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/GlobalOpt/const-return-status.ll
@@ -0,0 +1,28 @@
+; RUN: opt -globalopt < %s -S -o - | FileCheck %s
+
+; When simplifying users of a global variable, the pass could incorrectly
+; return false if there were still some uses left, and no further optimizations
+; was done. This was caught by the pass return status check that is hidden
+; under EXPENSIVE_CHECKS.
+
+; CHECK: @src = internal unnamed_addr constant
+
+; CHECK: entry:
+; CHECK-NEXT: %call = call i32 @f(i32 0)
+; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 4 bitcast (i32* @dst to i8*), i8* align 4 bitcast ([1 x i32]* @src to i8*), i64 1, i1 false)
+; CHECK-NEXT: ret void
+
+@src = internal unnamed_addr global [1 x i32] zeroinitializer, align 4
+@dst = external dso_local local_unnamed_addr global i32, align 4
+
+define dso_local void @d() local_unnamed_addr {
+entry:
+  %0 = load i32, i32* getelementptr inbounds ([1 x i32], [1 x i32]* @src, i64 0, i64 0), align 4
+  %call = call i32 @f(i32 %0)
+  call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 4 bitcast (i32* @dst to i8*), i8* align 4 bitcast ([1 x i32]* @src to i8*), i64 1, i1 false)
+  ret void
+}
+
+declare dso_local i32 @f(i32) local_unnamed_addr
+
+declare void @llvm.memcpy.p0i8.p0i8.i64(i8* noalias nocapture writeonly, i8* noalias nocapture readonly, i64, i1 immarg)