diff --git a/llvm/lib/Analysis/LoopAccessAnalysis.cpp b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
--- a/llvm/lib/Analysis/LoopAccessAnalysis.cpp
+++ b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
@@ -712,11 +712,12 @@
 
   // We assign a consecutive id to access from different alias sets.
   // Accesses between different groups doesn't need to be checked.
-  unsigned ASId = 1;
+  unsigned ASId = 0;
   for (auto &AS : AST) {
     int NumReadPtrChecks = 0;
     int NumWritePtrChecks = 0;
     bool CanDoAliasSetRT = true;
+    ++ASId;
 
     // We assign consecutive id to access from different dependence sets.
     // Accesses within the same set don't need a runtime check.
@@ -752,9 +753,25 @@
     // for which we couldn't find the bounds but we don't actually need to emit
     // any checks so it does not matter.
     bool NeedsAliasSetRTCheck = false;
-    if (!(IsDepCheckNeeded && CanDoAliasSetRT && RunningDepId == 2))
+    if (!(IsDepCheckNeeded && CanDoAliasSetRT && RunningDepId == 2)) {
       NeedsAliasSetRTCheck = (NumWritePtrChecks >= 2 ||
                              (NumReadPtrChecks >= 1 && NumWritePtrChecks >= 1));
+      // For alias sets without at least 2 writes or 1 write and 1 read, there
+      // is no need to generate RT checks and CanDoAliasSetRT for this alias set
+      // does not impact whether runtime checks can be generated.
+      if (!NeedsAliasSetRTCheck) {
+        assert(AS.size() <= 1 ||
+               all_of(AS,
+                      [this](auto AC) {
+                        MemAccessInfo AccessWrite(AC.getValue(), true);
+                        return DepCands.findValue(AccessWrite) ==
+                               DepCands.end();
+                      }) &&
+                   "Can only skip updating CanDoRT below, if all entries in AS "
+                   "are reads or there is at most 1 entry");
+        continue;
+      }
+    }
 
     // We need to perform run-time alias checks, but some pointers had bounds
     // that couldn't be checked.
@@ -774,7 +791,6 @@
 
     CanDoRT &= CanDoAliasSetRT;
     NeedRTCheck |= NeedsAliasSetRTCheck;
-    ++ASId;
   }
 
   // If the pointers that we would use for the bounds comparison have different