diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 79be162..6c41767 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -3479,10 +3479,14 @@
            UO->getOpcode() == UnaryOperator::Minus) &&
           Loc.isFileID() && UO->getOperatorLoc().isFileID() &&
           // Only if the two operators are exactly adjacent.
-          Loc.getFileLocWithOffset(1) == UO->getOperatorLoc())
+          Loc.getFileLocWithOffset(1) == UO->getOperatorLoc() &&
+          // And there is a space or other character before the subexpr of the
+          // unary +/-.  We don't want to warn on "x=-1".
+          Loc.getFileLocWithOffset(2) != UO->getSubExpr()->getLocStart()) {
         Diag(Loc, diag::warn_not_compound_assign)
           << (UO->getOpcode() == UnaryOperator::Plus ? "+" : "-")
           << SourceRange(UO->getOperatorLoc(), UO->getOperatorLoc());
+      }
     }
   } else {
     // Compound assignment "x += y"
diff --git a/test/Sema/exprs.c b/test/Sema/exprs.c
index ba411c5..45e1462 100644
--- a/test/Sema/exprs.c
+++ b/test/Sema/exprs.c
@@ -20,8 +20,11 @@
       static int var;
       var =+ 5;  // expected-warning {{use of unary operator that may be intended as compound assignment (+=)}}
       var =- 5;  // expected-warning {{use of unary operator that may be intended as compound assignment (-=)}}
-      var = +5;
+      var = +5;  // no warning when space between the = and +.
       var = -5;
+
+      var =+5;  // no warning when the subexpr of the unary op has no space before it.
+      var =-5;
 }
 
 // rdar://6319320