Index: llvm/lib/Transforms/IPO/SCCP.cpp
===================================================================
--- llvm/lib/Transforms/IPO/SCCP.cpp
+++ llvm/lib/Transforms/IPO/SCCP.cpp
@@ -83,6 +83,14 @@
                                  return !isOverdefined(LV);
                                });
                }
+
+               // We don't consider assume-like intrinsics to be actual address
+               // captures.
+               if (auto *II = dyn_cast<IntrinsicInst>(U)) {
+                 if (II->isAssumeLikeIntrinsic())
+                   return true;
+               }
+
                return !isOverdefined(Solver.getLatticeValueFor(U));
              }) &&
       "We can only zap functions where all live users have a concrete value");
@@ -336,10 +344,18 @@
     for (Argument &A : F->args())
       F->removeParamAttr(A.getArgNo(), Attribute::Returned);
     for (Use &U : F->uses()) {
-      // Skip over blockaddr users.
-      if (isa<BlockAddress>(U.getUser()))
+      CallBase *CB = dyn_cast<CallBase>(U.getUser());
+      if (!CB) {
+        assert(isa<BlockAddress>(U.getUser()) ||
+               (isa<Constant>(U.getUser()) &&
+                all_of(U.getUser()->users(), [](const User *UserUser) {
+                  return cast<IntrinsicInst>(UserUser)->isAssumeLikeIntrinsic();
+                })));
         continue;
-      CallBase *CB = cast<CallBase>(U.getUser());
+      }
+
+      // FIXME: Could this be a ConstantExpr cast user with a use in a call site
+      // that needs to be handled?
       for (Use &Arg : CB->args())
         CB->removeParamAttr(CB->getArgOperandNo(&Arg), Attribute::Returned);
     }
Index: llvm/test/Transforms/SCCP/issue59602-assume-like-call-users.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/SCCP/issue59602-assume-like-call-users.ll
@@ -0,0 +1,62 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature
+; RUN: opt -S -passes=ipsccp < %s | FileCheck %s
+
+@extern = global i32 0
+
+define i32 @call_assume_self_user() {
+; CHECK-LABEL: define {{[^@]+}}@call_assume_self_user() {
+; CHECK-NEXT:    [[CALL:%.*]] = call i32 @assume_self_user()
+; CHECK-NEXT:    ret i32 0
+;
+  %call = call i32 @assume_self_user()
+  ret i32 0
+}
+
+; Function address direct user is assume-like intrinsic.
+;
+; Make sure this doesn't hit "We can only zap functions where all live
+; users have a concrete value"
+define internal i32 @assume_self_user() {
+; CHECK-LABEL: define {{[^@]+}}@assume_self_user() {
+; CHECK-NEXT:    [[OBJSIZE:%.*]] = call i32 @llvm.objectsize.i32.p0(ptr @assume_self_user, i1 false, i1 false, i1 false)
+; CHECK-NEXT:    store i32 [[OBJSIZE]], ptr @extern, align 4
+; CHECK-NEXT:    ret i32 undef
+;
+  %objsize = call i32 @llvm.objectsize.i32.p0(ptr @assume_self_user, i1 false, i1 false, i1 false)
+  store i32 %objsize, ptr @extern
+  ret i32 0
+}
+
+
+; The objectsize call is an "assume like intrinsic" that can be
+; ignored for address taken purposes. The user of @constexpr_self_user
+; is a constant expression cast, so that the use call site does not
+; directly appear as a user.
+
+define i32 @callsite_with_returned() {
+; CHECK-LABEL: define {{[^@]+}}@callsite_with_returned() {
+; CHECK-NEXT:    [[CALL:%.*]] = call addrspace(1) i32 @constexpr_self_user(i32 123)
+; CHECK-NEXT:    ret i32 0
+;
+  %call = call addrspace(1) i32 @constexpr_self_user(i32 returned 123)
+  ret i32 0
+}
+
+; Has constexpr cast user in an assume-like intrinsic. Make sure we
+; don't assert on a cast<CallBase> for the user, and still remove
+; returned from the caller.
+define internal i32 @constexpr_self_user(i32 %arg0) addrspace(1) {
+; CHECK-LABEL: define {{[^@]+}}@constexpr_self_user
+; CHECK-SAME: (i32 [[ARG0:%.*]]) addrspace(1) {
+; CHECK-NEXT:    [[OBJSIZE:%.*]] = call i32 @llvm.objectsize.i32.p0(ptr addrspacecast (ptr addrspace(1) @constexpr_self_user to ptr), i1 false, i1 false, i1 false)
+; CHECK-NEXT:    store i32 [[OBJSIZE]], ptr @extern, align 4
+; CHECK-NEXT:    ret i32 undef
+;
+  %objsize = call i32 @llvm.objectsize.i32.p0(ptr addrspacecast (ptr addrspace(1) @constexpr_self_user to ptr), i1 false, i1 false, i1 false)
+  store i32 %objsize, ptr @extern
+  ret i32 %arg0
+}
+
+declare i32 @llvm.objectsize.i32.p0(ptr, i1 immarg, i1 immarg, i1 immarg) #0
+
+attributes #0 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }