Index: lib/Sema/SemaOpenMP.cpp
===================================================================
--- lib/Sema/SemaOpenMP.cpp
+++ lib/Sema/SemaOpenMP.cpp
@@ -10680,6 +10680,25 @@
           if (CI->getAssociatedDeclaration() != SI->getAssociatedDeclaration())
             break;
         }
+        // Check if the extra components of the expressions in the enclosing
+        // data environment are redundant for the current base declaration.
+        // If they are, the maps completely overlap, which is legal.
+        for (; SI != SE; ++SI) {
+          QualType Type;
+          if (auto *ASE =
+              dyn_cast<ArraySubscriptExpr>(SI->getAssociatedExpression())) {
+            Type = ASE->getBase()->IgnoreParenImpCasts()->getType();
+          } else if (auto *OASE =
+              dyn_cast<OMPArraySectionExpr>(SI->getAssociatedExpression())) {
+            auto *E = OASE->getBase()->IgnoreParenImpCasts();
+            Type =
+                OMPArraySectionExpr::getBaseOriginalType(E).getCanonicalType();
+          }
+          if (Type.isNull() || Type->isAnyPointerType() ||
+              CheckArrayExpressionDoesNotReferToWholeSize(
+                  SemaRef, SI->getAssociatedExpression(), Type))
+            break;
+        }
 
         // OpenMP 4.5 [2.15.5.1, map Clause, Restrictions, p.4]
         //  List items of map clauses in the same construct must not share
Index: test/OpenMP/target_map_messages.cpp
===================================================================
--- test/OpenMP/target_map_messages.cpp
+++ test/OpenMP/target_map_messages.cpp
@@ -284,6 +284,11 @@
     {}
   }
   }
+  #pragma omp target data map(marr[:][:][:])
+  {
+    #pragma omp target data map(marr)
+    {}
+  }
 
   #pragma omp target data map(to: t)
   {
@@ -419,10 +424,10 @@
 #pragma omp target data map(j)
 #pragma omp target map(l) map(l[:5]) // expected-error 2 {{variable already marked as mapped in current construct}} expected-note 2 {{used here}}
   foo();
-#pragma omp target data map(k[:4], j, l[:5]) // expected-note 4 {{used here}}
+#pragma omp target data map(k[:4], j, l[:5]) // expected-note 2 {{used here}}
 #pragma omp target data map(k) // expected-error 2 {{pointer cannot be mapped along with a section derived from itself}}
 #pragma omp target data map(j)
-#pragma omp target map(l) // expected-error 2 {{original storage of expression in data environment is shared but data environment do not fully contain mapped expression storage}}
+#pragma omp target map(l)
   foo();
 
 #pragma omp target data map(always, tofrom: x)
@@ -488,10 +493,10 @@
 #pragma omp target data map(j)
 #pragma omp target map(l) map(l[:5]) // expected-error {{variable already marked as mapped in current construct}} expected-note {{used here}}
   foo();
-#pragma omp target data map(k[:4], j, l[:5]) // expected-note 2 {{used here}}
+#pragma omp target data map(k[:4], j, l[:5]) // expected-note {{used here}}
 #pragma omp target data map(k) // expected-error {{pointer cannot be mapped along with a section derived from itself}}
 #pragma omp target data map(j)
-#pragma omp target map(l) // expected-error {{original storage of expression in data environment is shared but data environment do not fully contain mapped expression storage}}
+#pragma omp target map(l)
   foo();
 
 #pragma omp target data map(always, tofrom: x)
Index: test/OpenMP/target_parallel_for_map_messages.cpp
===================================================================
--- test/OpenMP/target_parallel_for_map_messages.cpp
+++ test/OpenMP/target_parallel_for_map_messages.cpp
@@ -143,13 +143,13 @@
   for (i = 0; i < argc; ++i) foo();
 #pragma omp target parallel for map(l) map(l[:5]) // expected-error 2 {{variable already marked as mapped in current construct}} expected-note 2 {{used here}}
   for (i = 0; i < argc; ++i) foo();
-#pragma omp target data map(k[:4], j, l[:5]) // expected-note 4 {{used here}}
+#pragma omp target data map(k[:4], j, l[:5]) // expected-note 2 {{used here}}
 {
 #pragma omp target parallel for map(k) // expected-error 2 {{pointer cannot be mapped along with a section derived from itself}}
   for (i = 0; i < argc; ++i) foo();
 #pragma omp target parallel for map(j)
   for (i = 0; i < argc; ++i) foo();
-#pragma omp target parallel for map(l) // expected-error 2 {{original storage of expression in data environment is shared but data environment do not fully contain mapped expression storage}}
+#pragma omp target parallel for map(l)
   for (i = 0; i < argc; ++i) foo();
 }
 
@@ -247,13 +247,13 @@
   for (i = 0; i < argc; ++i) foo();
 #pragma omp target parallel for map(l) map(l[:5]) // expected-error 1 {{variable already marked as mapped in current construct}} expected-note 1 {{used here}}
   for (i = 0; i < argc; ++i) foo();
-#pragma omp target data map(k[:4], j, l[:5]) // expected-note 2 {{used here}}
+#pragma omp target data map(k[:4], j, l[:5]) // expected-note {{used here}}
 {
 #pragma omp target parallel for map(k) // expected-error {{pointer cannot be mapped along with a section derived from itself}}
   for (i = 0; i < argc; ++i) foo();
 #pragma omp target parallel for map(j)
   for (i = 0; i < argc; ++i) foo();
-#pragma omp target parallel for map(l) // expected-error {{original storage of expression in data environment is shared but data environment do not fully contain mapped expression storage}}
+#pragma omp target parallel for map(l)
   for (i = 0; i < argc; ++i) foo();
 }
 
Index: test/OpenMP/target_parallel_for_simd_map_messages.cpp
===================================================================
--- test/OpenMP/target_parallel_for_simd_map_messages.cpp
+++ test/OpenMP/target_parallel_for_simd_map_messages.cpp
@@ -143,13 +143,13 @@
   for (i = 0; i < argc; ++i) foo();
 #pragma omp target parallel for simd map(l) map(l[:5]) // expected-error 2 {{variable already marked as mapped in current construct}} expected-note 2 {{used here}}
   for (i = 0; i < argc; ++i) foo();
-#pragma omp target data map(k[:4], j, l[:5]) // expected-note 4 {{used here}}
+#pragma omp target data map(k[:4], j, l[:5]) // expected-note 2 {{used here}}
 {
 #pragma omp target parallel for simd map(k) // expected-error 2 {{pointer cannot be mapped along with a section derived from itself}}
   for (i = 0; i < argc; ++i) foo();
 #pragma omp target parallel for simd map(j)
   for (i = 0; i < argc; ++i) foo();
-#pragma omp target parallel for simd map(l) // expected-error 2 {{original storage of expression in data environment is shared but data environment do not fully contain mapped expression storage}}
+#pragma omp target parallel for simd map(l)
   for (i = 0; i < argc; ++i) foo();
 }
 
@@ -247,13 +247,13 @@
   for (i = 0; i < argc; ++i) foo();
 #pragma omp target parallel for simd map(l) map(l[:5]) // expected-error 1 {{variable already marked as mapped in current construct}} expected-note 1 {{used here}}
   for (i = 0; i < argc; ++i) foo();
-#pragma omp target data map(k[:4], j, l[:5]) // expected-note 2 {{used here}}
+#pragma omp target data map(k[:4], j, l[:5]) // expected-note {{used here}}
 {
 #pragma omp target parallel for simd map(k) // expected-error {{pointer cannot be mapped along with a section derived from itself}}
   for (i = 0; i < argc; ++i) foo();
 #pragma omp target parallel for simd map(j)
   for (i = 0; i < argc; ++i) foo();
-#pragma omp target parallel for simd map(l) // expected-error {{original storage of expression in data environment is shared but data environment do not fully contain mapped expression storage}}
+#pragma omp target parallel for simd map(l)
   for (i = 0; i < argc; ++i) foo();
 }
 
Index: test/OpenMP/target_parallel_map_messages.cpp
===================================================================
--- test/OpenMP/target_parallel_map_messages.cpp
+++ test/OpenMP/target_parallel_map_messages.cpp
@@ -143,13 +143,13 @@
   foo();
 #pragma omp target parallel map(l) map(l[:5]) // expected-error 2 {{variable already marked as mapped in current construct}} expected-note 2 {{used here}}
   foo();
-#pragma omp target data map(k[:4], j, l[:5]) // expected-note 4 {{used here}}
+#pragma omp target data map(k[:4], j, l[:5]) // expected-note 2 {{used here}}
 {
 #pragma omp target parallel map(k) // expected-error 2 {{pointer cannot be mapped along with a section derived from itself}}
   foo();
 #pragma omp target parallel map(j)
   foo();
-#pragma omp target parallel map(l) // expected-error 2 {{original storage of expression in data environment is shared but data environment do not fully contain mapped expression storage}}
+#pragma omp target parallel map(l)
   foo();
 }
 
@@ -246,13 +246,13 @@
   foo();
 #pragma omp target parallel map(l) map(l[:5]) // expected-error 1 {{variable already marked as mapped in current construct}} expected-note 1 {{used here}}
   foo();
-#pragma omp target data map(k[:4], j, l[:5]) // expected-note 2 {{used here}}
+#pragma omp target data map(k[:4], j, l[:5]) // expected-note 1 {{used here}}
 {
 #pragma omp target parallel map(k) // expected-error {{pointer cannot be mapped along with a section derived from itself}}
   foo();
 #pragma omp target parallel map(j)
   foo();
-#pragma omp target parallel map(l) // expected-error {{original storage of expression in data environment is shared but data environment do not fully contain mapped expression storage}}
+#pragma omp target parallel map(l)
   foo();
 }