diff --git a/polly/lib/Support/SCEVValidator.cpp b/polly/lib/Support/SCEVValidator.cpp
index 24139908c5d7..0bece55de0ac 100644
--- a/polly/lib/Support/SCEVValidator.cpp
+++ b/polly/lib/Support/SCEVValidator.cpp
@@ -267,7 +267,14 @@ public:
     if (!Recurrence.isValid())
       return Recurrence;
 
-    if (R->contains(Expr->getLoop())) {
+    auto *L = Expr->getLoop();
+    if (R->contains(L) && (!Scope || !L->contains(Scope))) {
+      DEBUG(dbgs() << "INVALID: AddRec out of a loop whose exit value is not "
+                      "synthesizable");
+      return ValidatorResult(SCEVType::INVALID);
+    }
+
+    if (R->contains(L)) {
       if (Recurrence.isINT()) {
         ValidatorResult Result(SCEVType::IV);
         Result.addParamsFrom(Start);
diff --git a/polly/test/ScopDetect/index_from_unpredictable_loop.ll b/polly/test/ScopDetect/index_from_unpredictable_loop.ll
new file mode 100644
index 000000000000..fad59398ac2a
--- /dev/null
+++ b/polly/test/ScopDetect/index_from_unpredictable_loop.ll
@@ -0,0 +1,41 @@
+; RUN: opt %loadPolly -polly-scops -analyze < %s | FileCheck %s --check-prefix=AFFINE
+; RUN: opt %loadPolly -polly-scops -polly-allow-nonaffine -analyze < %s | FileCheck %s --check-prefix=NONAFFINE
+
+; The loop for.body => for.inc has an unpredictable iteration count could due to
+; the undef start value that it is compared to. Therefore the array element
+; %arrayidx101 that depends on that exit value cannot be affine.
+; Derived from test-suite/MultiSource/Benchmarks/BitBench/uuencode/uuencode.c
+
+define void @encode_line(i8* nocapture readonly %input, i32 %octets) {
+entry:
+  br i1 undef, label %for.body, label %for.end
+
+for.body:
+  %indvars.iv = phi i64 [ %indvars.iv.next, %for.inc ], [ 0, %entry ]
+  %octets.addr.02 = phi i32 [ undef, %for.inc ], [ %octets, %entry ]
+  br i1 false, label %for.inc, label %if.else
+
+if.else:
+  %cond = icmp eq i32 %octets.addr.02, 2
+  br i1 %cond, label %if.then84, label %for.end
+
+if.then84:
+  %0 = add nsw i64 %indvars.iv, 1
+  %arrayidx101 = getelementptr inbounds i8, i8* %input, i64 %0
+  %1 = load i8, i8* %arrayidx101, align 1
+  br label %for.end
+
+for.inc:
+  %cmp = icmp sgt i32 %octets.addr.02, 3
+  %indvars.iv.next = add nsw i64 %indvars.iv, 3
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:
+  ret void
+}
+
+
+; AFFINE-NOT: Function: encode_line
+
+; NONAFFINE:      Function: encode_line
+; NONAFFINE-NEXT: Region: %for.body---%for.end