diff --git a/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
--- a/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
@@ -449,6 +449,11 @@
 
   ProgramStateRef stateTrue, stateFalse;
 
+  // Assume different address spaces cannot overlap.
+  if (First.Expression->getType()->getPointeeType().getAddressSpace() !=
+      Second.Expression->getType()->getPointeeType().getAddressSpace())
+    return state;
+
   // Get the buffer values and make sure they're known locations.
   const LocationContext *LCtx = C.getLocationContext();
   SVal firstVal = state->getSVal(First.Expression, LCtx);
diff --git a/clang/test/Analysis/cstring-checker-addressspace.c b/clang/test/Analysis/cstring-checker-addressspace.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Analysis/cstring-checker-addressspace.c
@@ -0,0 +1,21 @@
+// RUN: %clang_analyze_cc1 -triple amdgcn-unknown-unknown \
+// RUN: -analyze -analyzer-checker=core,alpha.unix.cstring \
+// RUN: -analyze -analyzer-checker=debug.ExprInspection \
+// RUN: -analyzer-config crosscheck-with-z3=true -verify %s
+// REQUIRES: z3
+
+void clang_analyzer_warnIfReached();
+
+#define DEVICE __attribute__((address_space(256)))
+_Static_assert(sizeof(int *) == 4, "");
+_Static_assert(sizeof(DEVICE int *) == 8, "");
+
+// Copy from host to device memory.
+DEVICE void *memcpy(DEVICE void *dst, const void *src, unsigned long len);
+
+void top(DEVICE int *dst, int *src, int len) {
+  memcpy(dst, src, len);
+
+  // Create a bugreport for triggering Z3 refutation.
+  clang_analyzer_warnIfReached(); // expected-warning {{REACHABLE}}
+}