Index: flang/lib/Semantics/check-omp-structure.h
===================================================================
--- flang/lib/Semantics/check-omp-structure.h
+++ flang/lib/Semantics/check-omp-structure.h
@@ -190,6 +190,8 @@
       const parser::OmpObjectList &, const llvm::omp::Clause);
   void GetSymbolsInObjectList(
       const parser::OmpObjectList &, std::vector<const Symbol *> &);
+  void CheckWorkshareBlockStmts(
+      const parser::Block &, parser::CharBlock);
 };
 } // namespace Fortran::semantics
 #endif // FORTRAN_SEMANTICS_CHECK_OMP_STRUCTURE_H_
Index: flang/lib/Semantics/check-omp-structure.cpp
===================================================================
--- flang/lib/Semantics/check-omp-structure.cpp
+++ flang/lib/Semantics/check-omp-structure.cpp
@@ -130,6 +130,9 @@
   case llvm::omp::OMPD_parallel:
     CheckNoBranching(block, llvm::omp::OMPD_parallel, beginDir.source);
     break;
+  case llvm::omp::OMPD_workshare:
+    CheckWorkshareBlockStmts(block, beginDir.source);
+    break;
   default:
     break;
   }
@@ -728,4 +731,60 @@
   }
 }
 
+void OmpStructureChecker::CheckWorkshareBlockStmts(
+    const parser::Block &block, parser::CharBlock source) {
+  for (auto it{block.begin()}; it != block.end(); ++it) {
+    if (const auto *assignment{parser::Unwrap<parser::AssignmentStmt>(*it)}) {
+      const auto &var{std::get<parser::Variable>(assignment->t)};
+      const auto &expr{std::get<parser::Expr>(assignment->t)};
+      if (const auto *e{GetExpr(expr)}) {
+        for (const Symbol &symbol : evaluate::CollectSymbols(*e)) {
+          if (const Symbol * root{GetAssociationRoot(symbol)}) {
+            if (IsFunction(*root) &&
+                !(root->attrs().test(Attr::ELEMENTAL) ||
+                    root->attrs().test(Attr::INTRINSIC))) {
+              context_.Say(expr.source,
+                  "User defined non-ELEMENTAL function "
+                  "'%s' is not allowed in a WORKSHARE construct"_err_en_US,
+                  root->name());
+            }
+          }
+        }
+      }
+
+      const auto *rhs{GetExpr(expr)};
+      const auto *lhs{GetExpr(var)};
+      Tristate isDefined{semantics::IsDefinedAssignment(
+          lhs->GetType(), lhs->Rank(), rhs->GetType(), rhs->Rank())};
+      if (isDefined == Tristate::Yes) {
+        context_.Say(expr.source,
+            "Defined assignment statement is not "
+            "allowed in a WORKSHARE construct"_err_en_US);
+      }
+    } else if (const auto *ompBlock{
+                   parser::Unwrap<parser::OpenMPBlockConstruct>(*it)}) {
+      const auto &beginBlockDir{
+          std::get<parser::OmpBeginBlockDirective>(ompBlock->t)};
+      const auto &beginDir{
+          std::get<parser::OmpBlockDirective>(beginBlockDir.t)};
+      if (beginDir.v != llvm::omp::Directive::OMPD_parallel) {
+        context_.Say(source,
+            "OpenMP '%s' construct is not allowed "
+            "in a WORKSHARE construct"_err_en_US,
+            parser::ToUpperCaseLetters(getDirectiveName(beginDir.v).str()));
+      }
+    } else if (!(parser::Unwrap<parser::ForallConstruct>(*it) ||
+                   parser::Unwrap<parser::ForallStmt>(*it) ||
+                   parser::Unwrap<parser::WhereConstruct>(*it) ||
+                   parser::Unwrap<parser::WhereStmt>(*it) ||
+                   parser::Unwrap<parser::OpenMPAtomicConstruct>(*it) ||
+                   parser::Unwrap<parser::OpenMPCriticalConstruct>(*it))) {
+      context_.Say(source,
+          "The structured block in a WORKSHARE construct may consist of only "
+          "scalar or array assignments, forall or where statements, "
+          "forall, where, atomic, critical or parallel constructs"_err_en_US);
+    }
+  }
+}
+
 } // namespace Fortran::semantics
Index: flang/test/Semantics/omp-workshare01.f90
===================================================================
--- flang/test/Semantics/omp-workshare01.f90
+++ flang/test/Semantics/omp-workshare01.f90
@@ -1,6 +1,4 @@
 ! RUN: %S/test_errors.sh %s %t %f18 -fopenmp
-! XFAIL: *
-
 ! OpenMP Version 4.5
 ! 2.7.4 workshare Construct
 ! Invalid do construct inside !$omp workshare
@@ -9,8 +7,8 @@
   integer n, i
   real aa(n,n), bb(n,n), cc(n,n), dd(n,n), ee(n,n), ff(n,n)
 
+  !ERROR: The structured block in a WORKSHARE construct may consist of only scalar or array assignments, forall or where statements, forall, where, atomic, critical or parallel constructs
   !$omp workshare
-  !ERROR: Unexpected do stmt inside !$omp workshare
   do i = 1, n
     print *, "omp workshare"
   end do
Index: flang/test/Semantics/omp-workshare02.f90
===================================================================
--- flang/test/Semantics/omp-workshare02.f90
+++ flang/test/Semantics/omp-workshare02.f90
@@ -1,6 +1,4 @@
 ! RUN: %S/test_errors.sh %s %t %f18 -fopenmp
-! XFAIL: *
-
 ! OpenMP Version 4.5
 ! 2.7.4 workshare Construct
 ! The !omp workshare construct must not contain any user defined
@@ -20,7 +18,7 @@
   real aa(n,n), bb(n,n), cc(n,n), dd(n,n), ee(n,n), ff(n,n)
 
   !$omp workshare
-  !ERROR: Non-ELEMENTAL function is not allowed in !$omp workshare construct
+  !ERROR: User defined non-ELEMENTAL function 'my_func' is not allowed in a WORKSHARE construct
   aa = my_func(n)
   cc = dd
   ee = ff
Index: flang/test/Semantics/omp-workshare03.f90
===================================================================
--- /dev/null
+++ flang/test/Semantics/omp-workshare03.f90
@@ -0,0 +1,32 @@
+! RUN: %S/test_errors.sh %s %t %f18 -fopenmp
+! OpenMP Version 4.5
+! 2.7.4 workshare Construct
+! All array assignments, scalar assignments, and masked array assignments
+! must be intrinsic assignments.
+
+module defined_assign
+  interface assignment(=)
+    module procedure work_assign
+  end interface
+  
+  contains
+    subroutine work_assign(a,b)
+      integer , intent(out) :: a
+      logical , intent(in) :: b(:)
+    end subroutine work_assign
+end module defined_assign
+
+program omp_workshare
+  use defined_assign
+
+  integer:: a, aa(10), bb(10)
+  logical l(10)
+  l = .TRUE. 
+
+  !$omp workshare
+  !ERROR: Defined assignment statement is not allowed in a WORKSHARE construct
+  a = l
+  aa = bb
+  !$omp end workshare
+
+end program omp_workshare
Index: flang/test/Semantics/omp-workshare04.f90
===================================================================
--- /dev/null
+++ flang/test/Semantics/omp-workshare04.f90
@@ -0,0 +1,46 @@
+! RUN: %S/test_errors.sh %s %t %f18 -fopenmp
+! OpenMP Version 4.5
+! 2.7.4 workshare Construct
+! Checks for OpenMP Workshare construct
+
+subroutine omp_workshare(aa, bb, cc, dd, ee, ff, n)
+  integer i, j, n, a(10), b(10)
+  integer, pointer :: p
+  integer, target :: t
+  real aa(n,n), bb(n,n), cc(n,n), dd(n,n), ee(n,n), ff(n,n)
+
+  !ERROR: The structured block in a WORKSHARE construct may consist of only scalar or array assignments, forall or where statements, forall, where, atomic, critical or parallel constructs
+  !ERROR: OpenMP 'SINGLE' construct is not allowed in a WORKSHARE construct
+  !$omp workshare
+  p => t
+
+  !$omp parallel
+  cc = dd
+  !$omp end parallel
+
+  !$omp single
+  ee = ff
+  !$omp end single
+
+  where (aa .ne. 0) cc = bb / aa
+
+  where (b .lt. 2) b = sum(a)
+
+  where (aa .ge. 2.0)
+    cc = aa + bb
+  elsewhere 
+    cc = dd + ee
+  end where
+
+  forall (i = 1:10, n > i) a(i) = b(i)
+  
+  forall (j = 1:10)
+    a(j) = a(j) + b(j)
+  end forall
+
+  !$omp atomic update
+  j = j + sum(a)
+  
+  !$omp end workshare
+
+end subroutine omp_workshare