diff --git a/flang/include/flang/Frontend/CodeGenOptions.h b/flang/include/flang/Frontend/CodeGenOptions.h
--- a/flang/include/flang/Frontend/CodeGenOptions.h
+++ b/flang/include/flang/Frontend/CodeGenOptions.h
@@ -73,11 +73,12 @@
   // has
   // TODO: Share with clang instead of re-implementing here
   enum class RemarkKind {
-    RK_Missing,  // Remark argument not present on the command line.
-    RK_Enabled,  // Remark enabled via '-Rgroup', i.e. -Rpass, -Rpass-missed,
-                 // -Rpass-analysis
-    RK_Disabled, // Remark disabled via '-Rno-group', i.e. -Rno-pass,
-                 // -Rno-pass-missed, -Rno-pass-analysis.
+    RK_Missing,     // Remark argument not present on the command line.
+    RK_Enabled,     // Remark enabled via '-Rgroup', i.e. -Rpass, -Rpass-missed,
+                    // -Rpass-analysis
+    RK_Disabled,    // Remark disabled via '-Rno-group', i.e. -Rno-pass,
+                    // -Rno-pass-missed, -Rno-pass-analysis.
+    RK_WithPattern, // Remark pattern specified via '-Rgroup=regexp'.
   };
 
   /// Optimization remark with an optional regular expression pattern.
diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -156,7 +156,8 @@
 // Generate an OptRemark object containing info on if the -Rgroup
 // specified is enabled or not.
 static CodeGenOptions::OptRemark
-parseOptimizationRemark(llvm::opt::ArgList &args,
+parseOptimizationRemark(clang::DiagnosticsEngine &diags,
+                        llvm::opt::ArgList &args, llvm::opt::OptSpecifier optEq,
                         llvm::StringRef remarkOptName) {
   assert((remarkOptName == "pass" || remarkOptName == "pass-missed" ||
           remarkOptName == "pass-analysis") &&
@@ -180,6 +181,17 @@
         result.Pattern = "";
         result.Regex = nullptr;
       }
+    } else if (a->getOption().matches(optEq)) {
+      result.Kind = CodeGenOptions::RemarkKind::RK_WithPattern;
+      result.Pattern = a->getValue();
+      result.Regex = std::make_shared<llvm::Regex>(result.Pattern);
+      std::string regexError;
+
+      if (!result.Regex->isValid(regexError)) {
+        diags.Report(clang::diag::err_drv_optimization_remark_pattern)
+            << regexError << a->getAsString(args);
+        return CodeGenOptions::OptRemark();
+      }
     }
   }
   return result;
@@ -240,15 +252,18 @@
 
   // Create OptRemark that allows printing of all successful optimization
   // passes applied.
-  opts.OptimizationRemark = parseOptimizationRemark(args, "pass");
+  opts.OptimizationRemark = parseOptimizationRemark(
+      diags, args, clang::driver::options::OPT_Rpass_EQ, "pass");
 
   // Create OptRemark that allows all missed optimization passes to be printed.
-  opts.OptimizationRemarkMissed = parseOptimizationRemark(args, "pass-missed");
+  opts.OptimizationRemarkMissed = parseOptimizationRemark(
+      diags, args, clang::driver::options::OPT_Rpass_missed_EQ, "pass-missed");
 
   // Create OptRemark that allows all optimization decisions made by LLVM
   // to be printed.
-  opts.OptimizationRemarkAnalysis =
-      parseOptimizationRemark(args, "pass-analysis");
+  opts.OptimizationRemarkAnalysis = parseOptimizationRemark(
+      diags, args, clang::driver::options::OPT_Rpass_analysis_EQ,
+      "pass-analysis");
 
   if (auto *a = args.getLastArg(clang::driver::options::OPT_save_temps_EQ))
     opts.SaveTempsDir = a->getValue();
@@ -746,6 +761,9 @@
   res.getFrontendOpts().showColors =
       parseShowColorsArgs(args, /*defaultDiagColor=*/false);
 
+  // Honor color diagnostics.
+  res.getDiagnosticOpts().ShowColors = res.getFrontendOpts().showColors;
+
   return diags.getNumErrors() == numErrorsBefore;
 }
 
@@ -1010,8 +1028,15 @@
   // Preserve all the remark options requested, i.e. -Rpass, -Rpass-missed or
   // -Rpass-analysis. This will be used later when processing and outputting the
   // remarks generated by LLVM in ExecuteCompilerInvocation.cpp.
-  for (auto *a : args.filtered(clang::driver::options::OPT_R_Group))
-    res.getDiagnosticOpts().Remarks.push_back(a->getValue());
+  for (auto *a : args.filtered(clang::driver::options::OPT_R_Group)) {
+    if (a->getOption().matches(clang::driver::options::OPT_R_value_Group))
+      // This is -Rfoo=, where foo is the name of the diagnostic
+      // group. Add only the group name to the diagnostics.
+      res.getDiagnosticOpts().Remarks.push_back(
+          std::string(a->getOption().getName().drop_front(1).rtrim("=-")));
+    else
+      res.getDiagnosticOpts().Remarks.push_back(a->getValue());
+  }
 
   success &= parseFrontendArgs(res.getFrontendOpts(), args, diags);
   parseTargetArgs(res.getTargetOpts(), args);
diff --git a/flang/lib/FrontendTool/ExecuteCompilerInvocation.cpp b/flang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
--- a/flang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
+++ b/flang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
@@ -191,9 +191,6 @@
     return false;
   }
 
-  // Honor color diagnostics.
-  flang->getDiagnosticOpts().ShowColors = flang->getFrontendOpts().showColors;
-
   updateDiagEngineForOptRemarks(flang->getDiagnostics(),
                                 flang->getDiagnosticOpts());
 
diff --git a/flang/test/Driver/optimization-remark.f90 b/flang/test/Driver/optimization-remark.f90
--- a/flang/test/Driver/optimization-remark.f90
+++ b/flang/test/Driver/optimization-remark.f90
@@ -11,6 +11,18 @@
 ! RUN: %flang %s -O1 -Rno-pass-missed 2>&1 | FileCheck %s --allow-empty --check-prefix=NO-REMARKS
 ! RUN: %flang %s -O1 -Rno-pass-analysis 2>&1 | FileCheck %s --allow-empty --check-prefix=NO-REMARKS
 
+! Check error on invalid regex -Rpass message is emitted
+! RUN: not %flang %s -O1 -Rpass=[ 2>&1 | FileCheck %s --check-prefix=REGEX-INVALID
+
+! Check valid -Rpass regex
+! RUN: %flang %s -O1 -Rpass=loop 2>&1 | FileCheck %s
+
+! Check valid -Rpass-missed regex
+! RUN: %flang %s -O1 -Rpass-missed=loop 2>&1 | FileCheck %s --check-prefix=REMARKS-MISSED
+
+! Check valid -Rpass-analysis regex
+! RUN: %flang %s -O1 -Rpass-analysis=loop 2>&1 | FileCheck %s --check-prefix=REMARKS-ANALYSIS
+
 ! Check full -Rpass message is emitted
 ! RUN: %flang %s -O1 -Rpass 2>&1 | FileCheck %s
 
@@ -20,6 +32,7 @@
 ! Check full -Rpass-analysis message is emitted
 ! RUN: %flang %s -O1 -Rpass-analysis 2>&1 | FileCheck %s --check-prefix=REMARKS-ANALYSIS
 
+! REGEX-INVALID: error: in pattern '-Rpass=[': brackets ([ ]) not balanced
 ! CHECK: remark: Loop deleted because it is invariant
 ! REMARKS-MISSED: remark: loop not vectorized
 ! REMARKS-ANALYSIS: remark: loop not vectorized: instruction cannot be vectorized