diff --git a/fe/src/main/java/org/apache/impala/analysis/SlotDescriptor.java b/fe/src/main/java/org/apache/impala/analysis/SlotDescriptor.java
index f67ac8b53..e303a11ef 100644
--- a/fe/src/main/java/org/apache/impala/analysis/SlotDescriptor.java
+++ b/fe/src/main/java/org/apache/impala/analysis/SlotDescriptor.java
@@ -55,6 +55,8 @@ public class SlotDescriptor {
   private boolean isMaterialized_ = false;
 
   // if false, this slot cannot be NULL
+  // Note: it is still possible that a SlotRef pointing to this descriptor could have a
+  // NULL value if the entire tuple is NULL, for example as the result of an outer join.
   private boolean isNullable_ = true;
 
   // physical layout parameters
diff --git a/fe/src/main/java/org/apache/impala/rewrite/SimplifyConditionalsRule.java b/fe/src/main/java/org/apache/impala/rewrite/SimplifyConditionalsRule.java
index 287b4be1b..6d0b38c8f 100644
--- a/fe/src/main/java/org/apache/impala/rewrite/SimplifyConditionalsRule.java
+++ b/fe/src/main/java/org/apache/impala/rewrite/SimplifyConditionalsRule.java
@@ -103,8 +103,6 @@ public class SimplifyConditionalsRule implements ExprRewriteRule {
    * Simplify COALESCE by skipping leading nulls and applying the following transformations:
    * COALESCE(null, a, b) -> COALESCE(a, b);
    * COALESCE(<literal>, a, b) -> <literal>, when literal is not NullLiteral;
-   * COALESCE(<partition-slotref>, a, b) -> <partition-slotref>,
-   * when the partition column does not contain NULL.
    */
   private Expr simplifyCoalesceFunctionCallExpr(FunctionCallExpr expr) {
     int numChildren = expr.getChildren().size();
@@ -113,7 +111,7 @@ public class SimplifyConditionalsRule implements ExprRewriteRule {
       Expr childExpr = expr.getChildren().get(i);
       // Skip leading nulls.
       if (childExpr.isNullLiteral()) continue;
-      if ((i == numChildren - 1) || canSimplifyCoalesceUsingChild(childExpr)) {
+      if ((i == numChildren - 1) || childExpr.isLiteral()) {
         result = childExpr;
       } else if (i == 0) {
         result = expr;
@@ -126,32 +124,6 @@ public class SimplifyConditionalsRule implements ExprRewriteRule {
     return result;
   }
 
-  /**
-   * Checks if the given child expr is nullable. Returns true if one of the following holds:
-   * child is a non-NULL literal;
-   * child is a possibly cast SlotRef against a non-nullable slot;
-   * child is a possible cast SlotRef against a partition column that does not contain NULL.
-   */
-  private boolean canSimplifyCoalesceUsingChild(Expr child) {
-    if (child.isLiteral() && !child.isNullLiteral()) return true;
-
-    SlotRef slotRef = child.unwrapSlotRef(false);
-    if (slotRef == null) return false;
-    SlotDescriptor slotDesc = slotRef.getDesc();
-    if (!slotDesc.getIsNullable()) return true;
-    // Check partition column using partition metadata.
-    if (slotDesc.getParent().getTable() instanceof HdfsTable
-        && slotDesc.getColumn() != null
-        && slotDesc.getParent().getTable().isClusteringColumn(slotDesc.getColumn())) {
-      HdfsTable table = (HdfsTable) slotDesc.getParent().getTable();
-      // Return true if the partition column does not have a NULL value.
-      if (table.getNullPartitionIds(slotDesc.getColumn().getPosition()).isEmpty()) {
-        return true;
-      }
-    }
-    return false;
-  }
-
   private Expr simplifyFunctionCallExpr(FunctionCallExpr expr) {
     FunctionName fnName = expr.getFnName();
 
diff --git a/fe/src/test/java/org/apache/impala/analysis/ExprRewriteRulesTest.java b/fe/src/test/java/org/apache/impala/analysis/ExprRewriteRulesTest.java
index e49c6525f..4ff50a33b 100644
--- a/fe/src/test/java/org/apache/impala/analysis/ExprRewriteRulesTest.java
+++ b/fe/src/test/java/org/apache/impala/analysis/ExprRewriteRulesTest.java
@@ -398,20 +398,9 @@ public class ExprRewriteRulesTest extends FrontendTestBase {
     RewritesOk("coalesce(1 + 2, id, year)", rules, "3");
     RewritesOk("coalesce(null is null, bool_col)", rules, "TRUE");
     RewritesOk("coalesce(10 + null, id, year)", rules, "coalesce(id, year)");
-    // If the leading parameter is partition column, try to rewrite with partition metadata.
-    RewritesOk("coalesce(year, id)", rule, "year");
-    RewritesOk("coalesce(year, bigint_col)", rule, "year");
-    RewritesOk("coalesce(cast(year as string), string_col)", rule, "CAST(year AS STRING)");
-    RewritesOk("coalesce(id, year)", rule, null);
-    RewritesOk("coalesce(null, year, id)", rule, "year");
-    // If the leading partition column has NULL value, do not rewrite.
-    RewritesOk("functional.alltypesagg", "coalesce(year, id)", rule, "year");
-    RewritesOk("functional.alltypesagg", "coalesce(day, id)", rule, null);
-    // If the leading column is not nullable, rewrite to the column.
-    RewritesOk("functional_kudu.alltypessmall", "coalesce(id, year)", rule, "id");
-    RewritesOk("functional_kudu.alltypessmall", "coalesce(cast(id as string), string_col)", rule,
-        "CAST(id AS STRING)");
-    RewritesOk("functional_kudu.alltypessmall", "coalesce(null, id, year)", rule, "id");
+    // Don't rewrite based on nullability of slots. TODO (IMPALA-5753).
+    RewritesOk("coalesce(year, id)", rule, null);
+    RewritesOk("functional_kudu.alltypessmall", "coalesce(id, year)", rule, null);
   }
 
   @Test
diff --git a/testdata/workloads/functional-query/queries/QueryTest/exprs.test b/testdata/workloads/functional-query/queries/QueryTest/exprs.test
index d618a2497..9b1a1a73d 100644
--- a/testdata/workloads/functional-query/queries/QueryTest/exprs.test
+++ b/testdata/workloads/functional-query/queries/QueryTest/exprs.test
@@ -2741,4 +2741,26 @@ select if (true, 0, sum(id)) from functional.alltypestiny
 0
 ---- TYPES
 BIGINT
-====
\ No newline at end of file
+====
+---- QUERY
+# IMPALA-5725: test coalesce() is not rewritten when its first parameter is a non-nullable
+# Kudu column, but can have NULL values due to an outer join.
+select coalesce(b.id, a.id), b.id, a.id
+from functional_kudu.alltypes a left join functional_kudu.alltypestiny b on a.id = b.id
+where a.id = 100
+---- RESULTS
+100,NULL,100
+---- TYPES
+INT,INT,INT
+====
+---- QUERY
+# IMPALA-5725: test coalesce() is not rewritten when its first parameter is an HDFS
+# partition col with no NULL partitions, but can have NULL values due to an outer join.
+select coalesce(b.year, a.id), b.id, a.id
+from functional.alltypes a left join functional.alltypestiny b on a.id = b.id
+where a.id = 100
+---- RESULTS
+100,NULL,100
+---- TYPES
+INT,INT,INT
+====